Openshift Specific: Enable user workload monitoring for backstage

[tumido]

Hey, I think it would be nice to provide users with a simple switch to enable monitoring on the backstage instance.

This should include:

• ServiceMonitor for Backstage
• ServiceMonitor for PG cluster
• metrics exporter for PG
• Basic dashboard as a ConfigMap allowing users to easily import it if they choose to deploy a namespaced grafana (import it into GrafanaDashboard resource).

LMK if there would be interest for this feature and we can implement it.