feature: add kcp-aware MutatingAdmissionPolicy plugin

[gman0]

Feature Description

Kubernetes v1.32 adds MutatingAdmissionPolicy under admissionregistration.k8s.io/v1alpha1: https://kubernetes.io/docs/reference/access-authn-authz/mutating-admission-policy/

Proposed Solution

We may want to start thinking about incorporating it into kcp too, similar to the KCPValidatingAdmissionPolicy plugin.

Alternative Solutions

No response

Want to contribute?

• [ ] I would like to work on this issue.

Additional Context

No response

[gman0]

Let's also consider moving MAP-related informers and APIExport builtin types behind its respective feature gate.

[gman0]

I can take this.

/assign