Remove operatorkit dependency from rbac-operator / migrate to kubebuilder

[gawertm]

Towards #346

• rbac-operator
• organization-operator

Before releasing rbac-operator:

• https://github.com/giantswarm/giantswarm/issues/35270
• improve error handling in role binding template controller #2788

[anvddriesch]

For organization operator:
It would be quite easy to replace it just for CAPI installations since most functionality is deprecated in CAPI. Team also said they are up for it. Plus, we could add metrics easily.
We need to prioritize this @gawertm

[gawertm]

@anvddriesch what would be left here after @ssyno work of migrating organization operator.. should we do rbac-operator too?

[anvddriesch]

@gawertm I think we should.
That would require a lot more work though and we should refine it because it's possible that we can simplify some of the controllers.

[JosephSalisbury]

updating title to just "rbac-operator"