Allow executor preference for runners
Would be nice to specify multiple executor/resource types in a ranked preference order. I could have multiple self-hosted runner resource classes I've created, and if one has no nodes available, CircleCI moves down the list to the next resource class.
It would be nice if the list could also include cloud executor types - if none of my self-hosted runner classes have nodes available, then I default to using a CircleCI-hosted node.
This would be useful to me if and only if there was a way to trigger a cleanup script that runs at the end of a test run so I could tick-tock between a firmware flash job, and a job that runs hardware in the loop tests.
Runner config 1 would wait for a firmware update job, then kill itself and start runner config 2, which would wait for a test job (or timeout after a specified maximum wait time) and then once it's done it would kill itself and restart the firmware update job.