Is your feature request related to a problem? Please describe.
With the yaml based config and options inherited from cortex etc its easy to make mistakes in the loki config file that don't manifest until runtime. Right now the only way to test the config, per the team on Slack, is to run loki on it. This is fine for a manual check but it becomes difficult to work with in CI environments.

What would you like to be added:

1. use sidecarset inject initContainers

Why is this needed:

1. use sidecarset to replace istio webhook totally.
2. initContainers do not need inplace update
3. if mutiple sidecarsets inject mutiple initContainers in a pod , there is a simple solution that initContainers can be

containerizeds.standard.oam.dev is the schema for "Backend Worker" workload type, not definition, also, it should not be exposed to users of vela.

It should be sth like:

$ vela workloads
NAME         	DESCRIPTION                                                  
backend      	Backend worker without ports exposed          
task         	One-time off task or job
webservice