Add "Dockerfile" workflow running Hadolint

[szepeviktor]

This workflow will spot problems before Dockerfiles are used.

Warning

Hadolint is going to hurt your feelings!

source

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BTW I name workflows based on the object (noun), not the action (verb).
So the viktoroid version of tests.yml would be images.yml or docker-images.yml - meaning "Build images and Test images"

[szepeviktor]

If you are into OCI metadata: add this to .hadolint.yaml

# https://github.com/opencontainers/image-spec/blob/main/annotations.md#pre-defined-annotation-keys
label-schema:
    org.opencontainers.image.created: "rfc3339"
    org.opencontainers.image.authors: "text"
    org.opencontainers.image.url: "url"
    org.opencontainers.image.documentation: "url"
    org.opencontainers.image.source: "url"
    org.opencontainers.image.version: "semver"
    org.opencontainers.image.revision: "hash"
    org.opencontainers.image.vendor: "text"
    org.opencontainers.image.licenses: "spdx"
    org.opencontainers.image.ref.name: "text"
    org.opencontainers.image.title: "text"
    org.opencontainers.image.description: "text"
    # org.opencontainers.image.base.digest: "text"
    # org.opencontainers.image.base.name: "text"

[mnapoli]

I don't understand this PR, sorry.

[szepeviktor]

This PR adds a new workflow that run "Hadolint" on each commit.
Hadolint has dozens of rules to keep your Dockerfiles error-free on the long-term.

[szepeviktor]

It is better to close this one.
Hadolint is still available to you.