Add reconciler for EventPolicy

[creydr]

We need to add a reconciler for EventPolicies to update their status correctly. It should do the following:

• Resolve references / set EventPolicies .status.from (subs)
• Set .status.conditions:
  • AuthenticationEnabled to true if OIDC is enabled (Add authentication.oidc feature flag #7174) (and add watcher on feature flag configmap to update EventPolicies status if OIDC enabled/disabled)
  • SubjectsResolved to true if references are resolved
  • Ready, if the above are true

Prerequisites:

• Add EventPolicy type #7971
• Add Library to support on AuthZ #7985

Additional context:

• Feature track document

Additional hints for new contributors before starting with this issue:

1. When the issue has the Draft status, the issue is subject to change and thus should not be started to be worked on
2. Make sure you've read and understood the CONTRIBUTING.md guidelines
3. Make sure you're able to run Knative Eventing locally and run at least the unit tests.
4. Feel free to raise any questions you have either directly here in the issue, in the #knative-eventing Slack channel or join the Eventing Workgroup Meeting
5. When you feel comfortable with this issue, feel free to assign it to you (e.g. by commenting /assign). Please be aware that we might unassign you, if we don't see any progress from your side to give other contributors also a chance to work on this issue.

Open points:

• how to watch "all" references to get updates if they (/their .status.auth) changes?

[dharmjit]

Hi @creydr, If okay, I can take this up.

[creydr]

Hey @dharmjit,
sure. Would be great! Simply assign it to you. Only note, that not all other issues which are a prerequisite for this are done yet.

[dharmjit]

/assign

[creydr]

Hey @dharmjit,
as the prerequisite issues are resolved, this should be ready to be worked on (moved from "Backlog" to "Ready").