feat(cluster): Extend monitoring options with relabelings

[dragoangel]

Allow to customize resources as supported at https://cloudnative-pg.io/documentation/1.20/cloudnative-pg.v1/#postgresql-cnpg-io-v1-PoolerMonitoringConfiguration

[dragoangel]

Added customQueriesSecret as default list of secrets, so users who will use this chart as dependency can render their own secrets as they like (for example via vault-secret-operator), and have capability to point current chart to them. Current customQueries use ConfigMap and it will cover most of use cases, but in rare cases secrets also can be useful.