Deprecate ServiceMeshExtension (both v1alpha1 and v1)

In OSSM 2.2, we should deprecate ServiceMeshExtension, as we're shipping with WasmPlugin support, which is the upstream implementation and a superset of ServiceMeshExtension.

Acceptance Criteria:

• Release notes mention deprecation
• Wasm docs refer to WasmPlugin instead of ServiceMeshExtension
• 3scale team is aware of this change
• Creating ServiceMeshExtension resources triggers a deprecation warning in kubectl