expose runner-status in API

Describe the enhancement Today the api only exposes on/offline status: https://developer.github.com/v3/actions/self-hosted-runners/#list-self-hosted-runners-for-a-repository

It would be better if the API could show if the runner is occupied with a job or not (like in the UI).

We want to use this to dynamically provide self-hosted runners based on demand.

usecase:

1. package runner as docker image
2. have a k8s controller: https://github.com/evryfs/github-actions-runner-operator/
3. make runner spawn runners based on CRD high/low water marks and demand for runners.

Also - ideally there should be a possibility to add labels to runners, so that we can have different pools of runners for different environments. These labels should be reflected in the API so we can distinguish them both when listing runners, as well as using in jobs to select the appropriate type of runner.

Code Snippet status, enum of (online,offline,queued) (offline,idle,queued) labels, map of key: val

Additional information Killer feature for providing dynamic build-pools which again can help park Jenkins for good 😃

[hross]

I added this for internal discussion. I like the feature, I think it deserves some priority. Let me see where we can fit it…

[bryanmacfarlane]

I pinged some folks to at least get some 👀 on it 😃