Support for ACM cluster status

We need a replicate the logic ACM has for determining the status of a cluster (importing, etc.). Today this requires watching several different resources. The logic from ACM is here:

https://github.com/open-cluster-management/console/blob/main/frontend/src/lib/get-cluster.ts

This might not have any impact to the backend since the console backend can set up proxies to each cluster regardless of status. It would mainly impact the cluster selector where we might remove or disable items from the list if the clusters are not ready or are being torn down.