Displaying rabbit info through flux resource

[jameshcorbett]

@mcfadden8 requested that

flux resource allow for rabbit enumeration compute node grouping, status, and disk space usage.

This would require fetching a bunch of info out of fluxion. Although I believe the information of which rabbits map to which compute nodes (and vice versa) will soon be available as JSON on every compute node in a cluster.

Rabbit status is accessible in kubernetes, however normal users cannot access kubernetes.

@mcfadden8 also mentioned that he would

like to see flux drain/undrain also allow for rabbit status and manipulation.

This one I'm not so sure is a clear win. The command to drain or undrain a rabbit would just be a wrapper around kubectl patch. Kubernetes by design is the source of truth about rabbit status so flux would just be an intermediary. I could see it being useful perhaps for users to see which rabbits are down (as flux resource drain with no arguments does for compute nodes) but that might be covered by the flux resource list use case above if that could be implemented.