Proposal: Migration/Upgrade part for releasing the new CRD

[mfaizanse]

Since we now have the proposals for Subscription Spec and status, now we need to come up with the approach for upgrade scenario.

Objectives:

• [ ] Come up with a POC for how the upgrading from old CRD to new CRD will happen on existing clusters.
• [ ] Cover application connectivity and in-cluster eventing scenarios for both backends.
• [ ] The user should be able to create a subscription using the old CRD even after the new CRD is released.

Check out the tutorial on Kubebuilder documentation on how to release new CRD versions.

Open questions:

• Should we support the old and new version of the CRD. How should we depreciate the old CRD?
• Shall we transform the existing subscriptions into raw type in new CRD? Discuss in team for more info!
• Do we need pre-action in Eventing reconciler?

[mfaizanse]

TB: 5 days