Add Library to support on AuthZ

[creydr]

To support the EventPolicy implementation, we should have a library provinding the following functionality:

• Return all policies for a given target or resource
• Resolve the identity of a given reference (ref -> sub)
• Check if a subject (sub) is contained in a list of subs (.status.from) or matches a glob

In addition the OIDC library should be updated to provide the subject of a valid JWT.

Prerequisites:

• Add EventPolicy type #7971
• Add AppliedEventPoliciesStatus type #7975