Adding flux prometheus rule for CRD's and controller status

Description

Add prometheus rule template for alerting on Flux CRD's & basic state of controllers.

The first expression will capture all Flux CRD's in all namespaces and check for reconciliation errors (helm release / git repository / helm chart, alert, provider etc)

The second is a basic check for controller pod state. These are largely covered by existing generic kubernetes alerts - so not diving too deep down the rabbit hole on these ones.

Issues

Relates to https://repo1.dso.mil/platform-one/big-bang/bigbang/-/issues/1210