Add connection, permisison check to kubernetes work type

[kdelee]

Right now the only way to check if the kubernets cluster/credentials that the kubernetes work type is configured to use are correctly configured/the cluster is reachable is to actually submit work, e.g. launch a pod.

In AWX, which uses the receptor kubernetes work type as the way ContainerGroups connect and launch work on k8s/ocp, this translates to the only way to test a ContainerGroup is to actually launch a job. If we had this type of check, we could implement a "Test Connection" or periodic health check for the ContainerGroup

I'm not sure if the best way is to add options to https://github.com/ansible/receptor/blob/devel/docs/source/k8s.rst#runtime-params and have the kubernetes work type simply do something other than launch a pod (e.g. run equivalent of kubectl auth can-i --list or kubectl cluster-info) that can be called on command to check if the config is good/a work submit ought to work.

Another possible option I can imagine is defining some kind of "kubernetes-peer" like "tcp-peer" https://github.com/ansible/receptor/blob/devel/docs/source/connecting_nodes.rst#connecting-nodes where we specify a named "kubernetes-peer" with specified authmethod like in the kubernetes work type. Then we can "ping" this peer and perhaps that "ping" action will provide the desired "check if I can actually reach this cluster and what permissions I have"

Ideally, I'd like to also know things about the capacity of the k8s/ocp cluster, but that can come as an additional feature request later.