Provide status if runner is occupied with a job

[davidkarlsen]

Describe the enhancement
Be able to run a command like runner.sh jobstatus to tell if the runner is occupied with a job or not. This way I can block termination until it is free.

Code Snippet
N/A

Additional information
This will be used to drain k8s pods.

[TingluoHuang]

You could query GitHub REST API to get this info.
https://docs.github.com/en/rest/reference/actions#list-self-hosted-runners-for-a-repository

The service is the source of the truth for the actions system, don't rely on the runner.

[GMNGeoffrey]

I don't think this is a solution for several reasons: listing runners requires permissions that an entity with access to a single runner (for instance, the runner machine itself) may not (and should not) have, the server may have lost connection to the runner even if the runner is still processing a job, the network requests add additional latency that make it more likely that the result is outdated by the time it arrives. This is somewhat related to #745. The runner application itself should provide endpoints to monitor its status