Name already in use

Fixes: #710

- [ ] Did you write/update appropriate tests
- [x] Release notes updated (if appropriate)
- [ ] Appropriate logging output
- [X] Issue linked
- [x] Docs updated (or issue created)
https://docs.github.com/en/early-access/enterprise-importer/migrating-organizations-with-github-enterprise-importer/migrating-organizations-from-githubcom-to-github-enterprise-cloud

<!--
For docs we should review the docs at:

https://docs.github.com/en/early-access/github/migrating-with-github-enterprise-importer
and the README.md in this repo

If a doc update is required based on the changes in this PR, it is
sufficient to create an issue and link to it here. The doc update can be
made later/separately.

The process to update the docs can be found here:
https://github.com/github/docs-early-access#opening-prs

The markdown files are here: 

https://github.com/github/docs-early-access/tree/main/content/github/migrating-with-github-enterprise-importer
-->

<!--
For the checkboxes below you must check each one to indicate that you
either did the relevant task, or considered it and decided there was
nothing that needed doing
-->

Closes #718 

Adds `--bbs-project-key` to `bbs2gh generate-script` command.

- [x] Did you write/update appropriate tests
- [x] Release notes updated (if appropriate)
- [x] Appropriate logging output
- [x] Issue linked
- [x] Docs updated (or issue created)

<!--
For docs we should review the docs at:

https://docs.github.com/en/early-access/github/migrating-with-github-enterprise-importer
and the README.md in this repo

If a doc update is required based on the changes in this PR, it is
sufficient to create an issue and link to it here. The doc update can be
made later/separately.

The process to update the docs can be found here:
https://github.com/github/docs-early-access#opening-prs

The markdown files are here: 

https://github.com/github/docs-early-access/tree/main/content/github/migrating-with-github-enterprise-importer
-->

<!--
For the checkboxes below you must check each one to indicate that you
either did the relevant task, or considered it and decided there was
nothing that needed doing
-->

- [x] Did you write/update appropriate tests
- [x] Release notes updated (if appropriate)
- [x] Appropriate logging output
- [x] Issue linked
- [x] Docs updated (or issue created) (#715 )

This is the first pass on the requirements to migrate secret scanning
remediations between two repositories, provides the functionality for
#536.

This is being opened to start a code review and then complete the
support of this command line and service. There are some necessary
manual steps required as part of the larger migration in that the repo
is migrated and secret scanning has been reactivated (and the backfill
scan completed) before this command line makes sense to execute.

Created a new issue to add an integration test to cover this
functionality in the future: #717

<!--
For docs we should review the docs at:

https://docs.github.com/en/early-access/github/migrating-with-github-enterprise-importer
and the README.md in this repo

If a doc update is required based on the changes in this PR, it is
sufficient to create an issue and link to it here. The doc update can be
made later/separately.

The process to update the docs can be found here:
https://github.com/github/docs-early-access#opening-prs

The markdown files are here: 

https://github.com/github/docs-early-access/tree/main/content/github/migrating-with-github-enterprise-importer
-->

Co-authored-by: Peter Murray <peter-murray@users.noreply.github.com>
Co-authored-by: Arin Ghazarian <aringhazarian@github.com>
Co-authored-by: Dylan Smith <dylanfromwinnipeg@gmail.com>

<!--
For the checkboxes below you must check each one to indicate that you
either did the relevant task, or considered it and decided there was
nothing that needed doing
-->

Forgot to update integration-tests.yml in the [BBS integration tests
PR](#696).

Issue #553 

- [x] Did you write/update appropriate tests
- [x] Release notes updated (if appropriate)
- [x] Appropriate logging output
- [x] Issue linked
- [x] Docs updated (or issue created)

<!--
For docs we should review the docs at:

https://docs.github.com/en/early-access/github/migrating-with-github-enterprise-importer
and the README.md in this repo

If a doc update is required based on the changes in this PR, it is
sufficient to create an issue and link to it here. The doc update can be
made later/separately.

The process to update the docs can be found here:
https://github.com/github/docs-early-access#opening-prs

The markdown files are here: 

https://github.com/github/docs-early-access/tree/main/content/github/migrating-with-github-enterprise-importer
-->

<!--
For the checkboxes below you must check each one to indicate that you
either did the relevant task, or considered it and decided there was
nothing that needed doing
-->

Stood up a BBS server in our shared Azure Subscription
(e2e-bbs-8-5-0-linux-2204.eastus.cloudapp.azure.com). It's running the
latest version of BBS (8.5.0) and Ubuntu 22.04.

Manually created 2 projects and 2 repos in BBS (in the future we may
automate this like we have for ADO/GH), and added a new integration test
to migrate BBS->GH.

Included asserts to check if the GH repo exists and is initialized.

The default SSH cert that Azure generates didn't seem to work when using
Ubuntu 22.04 (didn't work with our SSH.Net nuget library, but did work
when directly using SSH in a terminal). I found a [workaround in an
issue](sshnet/SSH.NET#825 (comment))
from the SSH.Net repo that I applied in this PR. I don't fully
understand exactly what it's doing, but it looks like it's updating the
signature on the key in-memory before using it. Whatever it's doing, it
makes keys that previously didn't work now work. So it seems like a good
thing to me.

Closes #553 

Future work:
- automate the creation of BBS test data (like we do for ADO/GH)
- Include downloading the migration logs (and asserting that they exist)
- Add BBS windows server (once we support SMB)
- Add AWS
- Add another BBS server with the oldest version we support (5.14 I
think)

Checklist
- [x] Did you write/update appropriate tests
- [x] Release notes updated (if appropriate)
- [x] Appropriate logging output
- [x] Issue linked
- [x] Docs updated (or issue created)

<!--
For docs we should review the docs at:

https://docs.github.com/en/early-access/github/migrating-with-github-enterprise-importer
and the README.md in this repo

If a doc update is required based on the changes in this PR, it is
sufficient to create an issue and link to it here. The doc update can be
made later/separately.

The process to update the docs can be found here:
https://github.com/github/docs-early-access#opening-prs

The markdown files are here: 

https://github.com/github/docs-early-access/tree/main/content/github/migrating-with-github-enterprise-importer
-->

…os are migrated (#700)

When waiting for an organization-to-organization migration with the
`wait-for-migration` command, the only feedback that the CLI provides on
the progress of the migration is its `state`.

Org-to-org migrations potentially stay in the `REPO_MIGRATION` `state`
for a long time if there are many repos to be migrated, and this can be
a worrying time - as a user, you are likely to wonder "is my migration
actually moving forward"?.

The `node` query for `OrganizationMigration`s allows you to fetch the
`remainingRepositoriesCount` and `totalRepositoriesCount` for the
migration.

This commit starts grabbing that data and logging a progress indicator
(`1/10 repos migrated`) to the console.

Note that the GraphQL API currently returns `0` for the two count fields
if the number of repos has not yet been completed. There is an
outstanding bug to fix this and return `null` instead. This code is
future-proof, able to handle both values.

Fixes #699.

_I don't intend to make it a habit to make code changes, but I wanted to
see this enhancement added before org-to-org ships, and I wanted to get
familiar with the codebase 😊 _

<!--
For the checkboxes below you must check each one to indicate that you
either did the relevant task, or considered it and decided there was
nothing that needed doing
-->

- [x] Did you write/update appropriate tests
- [x] Release notes updated (if appropriate)
- [x] Appropriate logging output
- [x] Issue linked
- [x] Docs updated (or issue created)

<!--
For the checkboxes below you must check each one to indicate that you
either did the relevant task, or considered it and decided there was
nothing that needed doing
-->

Closes #668 

Our normal retry on failed GET's logic doesn't apply to GQL queries,
because technically they aren't doing a HTTP GET but rather a POST to
the GQL endpoint, so our retry logic doesn't kick in. They also aren't
always getting a normal HTTP error, instead they often are failing with
a HTTP 200 but with a GQL error message in the response body.

There are 9 places in `GithubApi` where we do a read-only query via GQL.
2 of those places are actually dead code that isn't used anywhere and I
deleted it:
- `GetOrganizationMigrationState`
- `GetMigrationStates`

6 instances where I updated the code to inspect the GQL response body
and check for any errors, and if so apply our normal retry logic:
- `GetOrganizationId`
- `GetEnterpriseId`
- `GetOrganizationMigration`
- `GetMigration`
- `GetMigrationLogUrl`
- `GetMannequins`

Then there was 1 instance where doing the retry logic will be a bit
trickier - `GetUserId` - because it assumes a GQL error means the user
doesn't exist and has some specific behavior in that scenario that
relies on it returning null instead of an exception. For this one I
didn't tackle it in this PR and created a new issue for us to tackle it
at some point in the future: #687

- [x] Did you write/update appropriate tests
- [x] Release notes updated (if appropriate)
- [x] Appropriate logging output
- [x] Issue linked
- [x] Docs updated (or issue created)

<!--
For docs we should review the docs at:

https://docs.github.com/en/early-access/github/migrating-with-github-enterprise-importer
and the README.md in this repo

If a doc update is required based on the changes in this PR, it is
sufficient to create an issue and link to it here. The doc update can be
made later/separately.

The process to update the docs can be found here:
https://github.com/github/docs-early-access#opening-prs

The markdown files are here: 

https://github.com/github/docs-early-access/tree/main/content/github/migrating-with-github-enterprise-importer
-->

<!--
For the checkboxes below you must check each one to indicate that you
either did the relevant task, or considered it and decided there was
nothing that needed doing
-->

Issue #678 

Added support for kerberos authentication when calling BBS API's. To do
this all we need to do is configure our HttpClient to have
`UseDefaultCredentials = true` and NOT set the normal Authorization
header that we set. This needs to be set at the time we construct the
HttpClient. Similar to how we did the NoSSL support, I added a couple
different named HttpClient's into our DI container ("Default" and
"Kerberos") configured appropriately. Then I added a new
`CreateKerberos()` function to `BbsApiFactory` that doesn't require a
username/password. Finally I added a 2nd constructor to `BbsApi` that
doesn't require a username/password and doesn't attempt to set the
Authorization header.

I added a `--kerberos` flag to both `bbs2gh generate-script` and `bbs2gh
migrate-repo`. For now this is a hidden option.

- [x] Did you write/update appropriate tests
- [x] Release notes updated (if appropriate)
- [x] Appropriate logging output
- [x] Issue linked
- [x] Docs updated (or issue created)

<!--
For docs we should review the docs at:

https://docs.github.com/en/early-access/github/migrating-with-github-enterprise-importer
and the README.md in this repo

If a doc update is required based on the changes in this PR, it is
sufficient to create an issue and link to it here. The doc update can be
made later/separately.

The process to update the docs can be found here:
https://github.com/github/docs-early-access#opening-prs

The markdown files are here: 

https://github.com/github/docs-early-access/tree/main/content/github/migrating-with-github-enterprise-importer
-->

…now a GitHub CLI extension (`gh ado2gh`) (#681)

When we shipped #653, we missed a case where omitting
`--azure-storage-connection-string` causes the app to crash, because
`AzureApiFactory.Create` was running anyway. After a bit of digging, I
discovered that we were using `AzureApi` to make unauthenticated HTTP
GETs to download the archives off of the GHES instance. This PR moves
`AzureApi.DownloadArchive` into its own class, so that we can
encapsulate making unauthenticated HTTP GETs.


- [x] Did you write/update appropriate tests
- [x] Release notes updated (if appropriate)
- [x] Appropriate logging output
- [ ] Issue linked
- [ ] Docs updated (or issue created)

<!--
For docs we should review the docs at:

https://docs.github.com/en/early-access/github/migrating-with-github-enterprise-importer
and the README.md in this repo

If a doc update is required based on the changes in this PR, it is
sufficient to create an issue and link to it here. The doc update can be
made later/separately.

The process to update the docs can be found here:
https://github.com/github/docs-early-access#opening-prs

The markdown files are here: 

https://github.com/github/docs-early-access/tree/main/content/github/migrating-with-github-enterprise-importer
-->

<!--
For the checkboxes below you must check each one to indicate that you
either did the relevant task, or considered it and decided there was
nothing that needed doing
-->

Changed hte last of hte commands to use the new patterns, with factories
no longer appearing in the Handlers.

Issue #639 

- [x] Did you write/update appropriate tests
- [x] Release notes updated (if appropriate)
- [x] Appropriate logging output
- [x] Issue linked
- [x] Docs updated (or issue created)

<!--
For docs we should review the docs at:

https://docs.github.com/en/early-access/github/migrating-with-github-enterprise-importer
and the README.md in this repo

If a doc update is required based on the changes in this PR, it is
sufficient to create an issue and link to it here. The doc update can be
made later/separately.

The process to update the docs can be found here:
https://github.com/github/docs-early-access#opening-prs

The markdown files are here: 

https://github.com/github/docs-early-access/tree/main/content/github/migrating-with-github-enterprise-importer
-->

<!--
For the checkboxes below you must check each one to indicate that you
either did the relevant task, or considered it and decided there was
nothing that needed doing
-->

Closes #594.
Related to github/releases#2532.

- [ ] Did you write/update appropriate tests
- [ ] Release notes updated (if appropriate)
- [ ] Appropriate logging output
- [ ] Issue linked
- [ ] Docs updated (or issue created)

<!--
For docs we should review the docs at:

https://docs.github.com/en/early-access/github/migrating-with-github-enterprise-importer
and the README.md in this repo

If a doc update is required based on the changes in this PR, it is
sufficient to create an issue and link to it here. The doc update can be
made later/separately.

The process to update the docs can be found here:
https://github.com/github/docs-early-access#opening-prs

The markdown files are here: 

https://github.com/github/docs-early-access/tree/main/content/github/migrating-with-github-enterprise-importer
-->

Co-authored-by: Dean Tambling <tambling@github.com>
Co-authored-by: Arin Ghazarian <aringhazarian@github.com>

Fixes: github/octoshift#5627

This PR retrieves and displays the failure reason for org migrations
which is now available in the graphql query.
Minor header related changes have also been made since we no longer
require the `internal` header.


<!--
For the checkboxes below you must check each one to indicate that you
either did the relevant task, or considered it and decided there was
nothing that needed doing
-->

- [x] Did you write/update appropriate tests
- [x] Release notes updated (if appropriate)
- [x] Appropriate logging output
- [x] Issue linked
- [x] Docs updated (or issue created)

<!--
For docs we should review the docs at:

https://docs.github.com/en/early-access/github/migrating-with-github-enterprise-importer
and the README.md in this repo

If a doc update is required based on the changes in this PR, it is
sufficient to create an issue and link to it here. The doc update can be
made later/separately.

The process to update the docs can be found here:
https://github.com/github/docs-early-access#opening-prs

The markdown files are here: 

https://github.com/github/docs-early-access/tree/main/content/github/migrating-with-github-enterprise-importer
-->

<!--
For the checkboxes below you must check each one to indicate that you
either did the relevant task, or considered it and decided there was
nothing that needed doing
-->
Closes #600 

This PR adds the ability to specify a GHES API Url to the
`GrantMigratorRole` and `RevokeMigratorRole` commands via the
`--ghes-api-url` flag.

- [x] Did you write/update appropriate tests
- [x] Release notes updated (if appropriate)
- [x] Appropriate logging output
- [x] Issue linked
- [x] Docs updated (or issue created)

<!--
For docs we should review the docs at:

https://docs.github.com/en/early-access/github/migrating-with-github-enterprise-importer
and the README.md in this repo

If a doc update is required based on the changes in this PR, it is
sufficient to create an issue and link to it here. The doc update can be
made later/separately.

The process to update the docs can be found here:
https://github.com/github/docs-early-access#opening-prs

The markdown files are here: 

https://github.com/github/docs-early-access/tree/main/content/github/migrating-with-github-enterprise-importer
-->

Co-authored-by: Arin Ghazarian <aringhazarian@github.com>

<!--
For the checkboxes below you must check each one to indicate that you
either did the relevant task, or considered it and decided there was
nothing that needed doing
-->

The final refactoring for bbs2gh. Changed the way we construct commands
and the dependency graph to the final state.

More PR's to follow for the other projects.

Issue #639

- [x] Did you write/update appropriate tests
- [x] Release notes updated (if appropriate)
- [x] Appropriate logging output
- [x] Issue linked
- [x] Docs updated (or issue created)

<!--
For docs we should review the docs at:

https://docs.github.com/en/early-access/github/migrating-with-github-enterprise-importer
and the README.md in this repo

If a doc update is required based on the changes in this PR, it is
sufficient to create an issue and link to it here. The doc update can be
made later/separately.

The process to update the docs can be found here:
https://github.com/github/docs-early-access#opening-prs

The markdown files are here: 

https://github.com/github/docs-early-access/tree/main/content/github/migrating-with-github-enterprise-importer
-->

<!--
For the checkboxes below you must check each one to indicate that you
either did the relevant task, or considered it and decided there was
nothing that needed doing
-->

Improved unit test performance from 2.4 minutes to 26 seconds.

We had a bunch of unit tests that we're doing retries with up to 10
seconds wait times between retries. I changed it to be 0 wait time where
possible, and 1 second wait in a couple places where 0 wouldn't work.

- [x] Did you write/update appropriate tests
- [x] Release notes updated (if appropriate)
- [x] Appropriate logging output
- [x] Issue linked
- [x] Docs updated (or issue created)

<!--
For docs we should review the docs at:

https://docs.github.com/en/early-access/github/migrating-with-github-enterprise-importer
and the README.md in this repo

If a doc update is required based on the changes in this PR, it is
sufficient to create an issue and link to it here. The doc update can be
made later/separately.

The process to update the docs can be found here:
https://github.com/github/docs-early-access#opening-prs

The markdown files are here: 

https://github.com/github/docs-early-access/tree/main/content/github/migrating-with-github-enterprise-importer
-->

<!--
For the checkboxes below you must check each one to indicate that you
either did the relevant task, or considered it and decided there was
nothing that needed doing
-->

Fixes #657 

When we switched to shipping `ado2gh` as a `gh` extension a couple
releases ago we didn't update `ado2gh generate-script`, so the migration
script it was generating was still trying to run the stand-alone
`ado2gh` instead of the `gh` extension.

- [x] Did you write/update appropriate tests
- [x] Release notes updated (if appropriate)
- [x] Appropriate logging output
- [x] Issue linked
- [x] Docs updated (or issue created)

<!--
For docs we should review the docs at:

https://docs.github.com/en/early-access/github/migrating-with-github-enterprise-importer
and the README.md in this repo

If a doc update is required based on the changes in this PR, it is
sufficient to create an issue and link to it here. The doc update can be
made later/separately.

The process to update the docs can be found here:
https://github.com/github/docs-early-access#opening-prs

The markdown files are here: 

https://github.com/github/docs-early-access/tree/main/content/github/migrating-with-github-enterprise-importer
-->

<!--
For the checkboxes below you must check each one to indicate that you
either did the relevant task, or considered it and decided there was
nothing that needed doing
-->

Split out a CommandHandler class for all the shared commands in
Octoshift. This is in preparation for the next step in the refactor
where we will change how we wire up the command/handlers using some new
binding/reflection code.

Issue #638 

- [x] Did you write/update appropriate tests
- [x] Release notes updated (if appropriate)
- [x] Appropriate logging output
- [x] Issue linked
- [x] Docs updated (or issue created)

<!--
For docs we should review the docs at:

https://docs.github.com/en/early-access/github/migrating-with-github-enterprise-importer
and the README.md in this repo

If a doc update is required based on the changes in this PR, it is
sufficient to create an issue and link to it here. The doc update can be
made later/separately.

The process to update the docs can be found here:
https://github.com/github/docs-early-access#opening-prs

The markdown files are here: 

https://github.com/github/docs-early-access/tree/main/content/github/migrating-with-github-enterprise-importer
-->

Related to #639

This is all the required infrastructure changes in form of some
extension method to do the plumbing for the new CommandLine. Here is a
[sample
branch](https://github.com/github/gh-gei/tree/upgrade-bbs2gh-to-new-command-line)
that applies these changes to `bbs2gh`.
I went ahead and simplified it even more by creating an extension to add
all commands to the `rootCommand`. Here is how it's supposed to be used:

```c#
public static async Task<int> Main(string[] args) // note that Main now returns a Task<int> instead of Task
{
    Logger.LogDebug("Execution Started");
 
    var serviceCollection = new ServiceCollection();
    ... // service registrations
    var serviceProvider = serviceCollection.BuildServiceProvider();

    var rootCommand = new RootCommand("Automate end-to-end Bitbucket Server to GitHub migrations.")
          .AddCommands(serviceProvider);

    ...
}
```

- [x] Did you write/update appropriate tests
- [x] Release notes updated (if appropriate)
- [x] Appropriate logging output
- [x] Issue linked
- [x] Docs updated (or issue created)

Co-authored-by: Dylan Smith <dylan-smith@github.com>
Co-authored-by: Dylan Smith <dylanfromwinnipeg@gmail.com>

<!--
For the checkboxes below you must check each one to indicate that you
either did the relevant task, or considered it and decided there was
nothing that needed doing
-->

Split the unit tests into separate files for CommandTests and
CommandHandlerTests.

Closes #638 

- [x] Did you write/update appropriate tests
- [x] Release notes updated (if appropriate)
- [x] Appropriate logging output
- [x] Issue linked
- [x] Docs updated (or issue created)

<!--
For docs we should review the docs at:

https://docs.github.com/en/early-access/github/migrating-with-github-enterprise-importer
and the README.md in this repo

If a doc update is required based on the changes in this PR, it is
sufficient to create an issue and link to it here. The doc update can be
made later/separately.

The process to update the docs can be found here:
https://github.com/github/docs-early-access#opening-prs

The markdown files are here: 

https://github.com/github/docs-early-access/tree/main/content/github/migrating-with-github-enterprise-importer
-->

<!--
For the checkboxes below you must check each one to indicate that you
either did the relevant task, or considered it and decided there was
nothing that needed doing
-->

Split out a CommandHandler class for all the shared commands in
Octoshift. This is in preparation for the next step in the refactor
where we will change how we wire up the command/handlers using some new
binding/reflection code.

Issue #638 

- [x] Did you write/update appropriate tests
- [x] Release notes updated (if appropriate)
- [x] Appropriate logging output
- [x] Issue linked
- [x] Docs updated (or issue created)

<!--
For docs we should review the docs at:

https://docs.github.com/en/early-access/github/migrating-with-github-enterprise-importer
and the README.md in this repo

If a doc update is required based on the changes in this PR, it is
sufficient to create an issue and link to it here. The doc update can be
made later/separately.

The process to update the docs can be found here:
https://github.com/github/docs-early-access#opening-prs

The markdown files are here: 

https://github.com/github/docs-early-access/tree/main/content/github/migrating-with-github-enterprise-importer
-->

<!--
For the checkboxes below you must check each one to indicate that you
either did the relevant task, or considered it and decided there was
nothing that needed doing
-->

Split out a CommandHandler class for all the gei commands. This is in
preparation for the next step in the refactor where we will change how
we wire up the command/handlers using some new binding/reflection code.

There will be more PR's to follow with the rest of the commands.

Issue #638 

- [x] Did you write/update appropriate tests
- [x] Release notes updated (if appropriate)
- [x] Appropriate logging output
- [x] Issue linked
- [x] Docs updated (or issue created)

<!--
For docs we should review the docs at:

https://docs.github.com/en/early-access/github/migrating-with-github-enterprise-importer
and the README.md in this repo

If a doc update is required based on the changes in this PR, it is
sufficient to create an issue and link to it here. The doc update can be
made later/separately.

The process to update the docs can be found here:
https://github.com/github/docs-early-access#opening-prs

The markdown files are here: 

https://github.com/github/docs-early-access/tree/main/content/github/migrating-with-github-enterprise-importer
-->

<!--
For the checkboxes below you must check each one to indicate that you
either did the relevant task, or considered it and decided there was
nothing that needed doing
-->
When you use an environment variable to pass a secret in (as is
recommended) we are properly scrubbing them from the logs
(EnvironmentVariableProvider is calling OctoLogger.RegisterSecret).
However, if a secret comes in via a command-line arg (e.g.
`--github-pat`) we aren't registering it as a secret with the logger,
and it will show up in the log files.

This PR updates every command that accepts secrets to call
RegisterSecret for each one.

Closes #618 

- [x] Did you write/update appropriate tests
- [x] Release notes updated (if appropriate)
- [x] Appropriate logging output
- [x] Issue linked
- [x] Docs updated (or issue created)

<!--
For docs we should review the docs at:

https://docs.github.com/en/early-access/github/migrating-with-github-enterprise-importer
and the README.md in this repo

If a doc update is required based on the changes in this PR, it is
sufficient to create an issue and link to it here. The doc update can be
made later/separately.

The process to update the docs can be found here:
https://github.com/github/docs-early-access#opening-prs

The markdown files are here: 

https://github.com/github/docs-early-access/tree/main/content/github/migrating-with-github-enterprise-importer
-->

<!--
For the checkboxes below you must check each one to indicate that you
either did the relevant task, or considered it and decided there was
nothing that needed doing
-->

Split out a CommandHandler class for all the ado2gh commands. This is in
preparation for the next step in the refactor where we will change how
we wire up the command/handlers using some new binding/reflection code.

There will be more PR's to follow with the rest of the commands.

Issue #638 

- [x] Did you write/update appropriate tests
- [x] Release notes updated (if appropriate)
- [x] Appropriate logging output
- [x] Issue linked
- [x] Docs updated (or issue created)

<!--
For docs we should review the docs at:

https://docs.github.com/en/early-access/github/migrating-with-github-enterprise-importer
and the README.md in this repo

If a doc update is required based on the changes in this PR, it is
sufficient to create an issue and link to it here. The doc update can be
made later/separately.

The process to update the docs can be found here:
https://github.com/github/docs-early-access#opening-prs

The markdown files are here: 

https://github.com/github/docs-early-access/tree/main/content/github/migrating-with-github-enterprise-importer
-->

<!--
For the checkboxes below you must check each one to indicate that you
either did the relevant task, or considered it and decided there was
nothing that needed doing
-->
Refactored all remaining commands in Octoshift/gei/ado2gh to use Args
classes. Didn't touch bbs2gh yet.

For gei commands that inherit from an Octoshift shared command class
then change an arg name, we had duplicate the Args class, and do a bit
of mapping code in the sub-classed command. This bit of cruft will go
away with the last step of this refactor when we change how we map
command-line options to the Args class using a custom binder.

Part of #637 

- [x] Did you write/update appropriate tests
- [x] Release notes updated (if appropriate)
- [x] Appropriate logging output
- [x] Issue linked
- [x] Docs updated (or issue created)

<!--
For docs we should review the docs at:

https://docs.github.com/en/early-access/github/migrating-with-github-enterprise-importer
and the README.md in this repo

If a doc update is required based on the changes in this PR, it is
sufficient to create an issue and link to it here. The doc update can be
made later/separately.

The process to update the docs can be found here:
https://github.com/github/docs-early-access#opening-prs

The markdown files are here: 

https://github.com/github/docs-early-access/tree/main/content/github/migrating-with-github-enterprise-importer
-->

<!--
For the checkboxes below you must check each one to indicate that you
either did the relevant task, or considered it and decided there was
nothing that needed doing
-->
This is part of the refactor to upgrade System.CommandLine. This is step
1 of the incremental refactor plan: getting all our commands to
consistently use an Args class to capture all arguments.

This applies the refactoring to all the ado2gh commands (but not the
common commands from Octoshift).

Part of #637 

- [x] Did you write/update appropriate tests
- [x] Release notes updated (if appropriate)
- [x] Appropriate logging output
- [x] Issue linked
- [x] Docs updated (or issue created)

<!--
For docs we should review the docs at:

https://docs.github.com/en/early-access/github/migrating-with-github-enterprise-importer
and the README.md in this repo

If a doc update is required based on the changes in this PR, it is
sufficient to create an issue and link to it here. The doc update can be
made later/separately.

The process to update the docs can be found here:
https://github.com/github/docs-early-access#opening-prs

The markdown files are here: 

https://github.com/github/docs-early-access/tree/main/content/github/migrating-with-github-enterprise-importer
-->