[Task] Promote CRDs to v1beta1

[sdischer-sap]

Is your feature request related to a problem? Please describe.
Most resources are already well tested and proved to be quite mature out in the field. Leaving them all in v1alpha1 does not feel appropriate anymore for those.

Describe the solution you'd like
Come up with a clear guideline on criterias and processes when and how to promote CRDs. Apply it by promoting CRDs where required to fulfill those guidelines.

[JohannesRu]

What we currently state as maturity:

By @mirzakopic

Automated test I'd argue as:

• automated e2e test
• unit test
• automated version upgrade test ~(resource orchestrated by provider 1.0 still works with provider 1.3)

[sdischer-sap]

Yes exactly, this would pretty much make all of our resources v1 already, but I am not sure I am comfortable with that since we are still discussing some potential schema changes here and there or even exchanging the underlying tech to terraform based.
Also we still haven't ever done some automatic schema migration, which probably should be a perquisite for that as well.

I will prepare some key questions and potential action items to base another discussion on.