watch namespaces using a label selector

[atos-cosmin-gavagiuc]

Is your feature request related to a problem? Please describe. I want to watch namespaces using a label selector for the purpose of running multiple Grafana operators in the same cluster.

Describe the solution you'd like Add WATCH_NAMESPACE_SELECTOR env variable. Example: WATCH_NAMESPACE_SELECTOR="environment: dev" In the controller runtime build a list of namespaces with label environment: dev and pass it to controllerOptions.Cache.DefaultNamespaces