Implement PolicyGroups RFC

[viccuad]

Implement RFC PolicyGroups.

Acceptance criteria

• Add PolicyGroups to policy-server. This includes changing policy-evaluator. feat: introduce group policies policy-server#814
• Add PolicyGroups CRD to kubewarden-controller #833
  • Define the CRDs Go types.
  • Implement the reconciliation of the new CRDs, make sure we can reuse as much as possible of the sub-reconciler we already have in place.
• Add PolicyGroup to the helm chart, remove feature flag from controller #857
• Extend kubewarden-controller admission webhook: it must validate the CEL expression defined inside of the new CRDs #859
• PolicyGroups CRDs do not match PolicyServer config #872
• Validate PolicyGroup members name #876
• Support PolicyGroups in Audit Scanner audit-scanner#366
• Refactor policy interface #842
• Extend CRD and add matchConditions (optional). #858
• Docs:
  • Add PolicyGroup to the helm chart, remove feature flag from controller #857
  • Add explanation page.
  • Add HowTo page
• Blogpost.
• Add PolicyGroups to kwctl (kwctl run, kwctl scaffold) [Optional]

[flavio]

This has been done now