Create and publish Monitoring functional layer

[mjnagel]

Additional context in #736

As accepted in the ADR we should create and publish a "Monitoring" functional layer. This layer should include Grafana and Prometheus.

Definition of done for this layer:

• New packages/monitoring folder with a zarf.yaml named core-monitoring importing grafana and prometheus (plus CRDs)
• Readme identifying the contents of the layer as well as any dependency layers (base and identity-authorization in this case)
• Validation task file, importing validations from components
• CI filters modified to test "monitoring" on changes to appropriate files
• CI workflows/tasks modified to add a "layer test" which builds and deploys the specified layer. This should be used on the CI filter in place of the existing single package test for the relevant package(s)
• Publishing workflows/tasks updated to publish the layer, using monolithic versioning (versioned identical to core itself) - this will also require release-please config updates
• Updating pepr/operator code to properly handle reconciliation when monitoring is not present (i.e. skip service/pod monitoring creation). Also ideally create warning events when a Package CR contains monitor configuration if this layer is not deployed (some initial draft changes were made to partially handle this with watches)

Existing draft PR may be helpful in the implementation here.