Validation: remove CEL for PolicyTargetRef to allow vendor extensions (#3414)

* Validation: CEL adjusted to allow PolicyTargetReference to target gtwapi GatewayClass

Signed-off-by: Ian Rudie <ian.rudie@solo.io>

* adding releasenote

Signed-off-by: Ian Rudie <ian.rudie@solo.io>

* remove CEL validations for PolicyTargetRef to allow vendor extensions

Signed-off-by: Ian Rudie <ian.rudie@solo.io>

* remove centralized group/kind detail and move to where targetRef is used in resources

Signed-off-by: Ian Rudie <ian.rudie@solo.io>

---------

Signed-off-by: Ian Rudie <ian.rudie@solo.io>

Author: ilrudie

extensions/v1alpha1/wasm.pb.go

@@ -257,7 +257,9 @@ message WasmPlugin {
   //
   // Currently, the following resource attachment types are supported:
   // * `kind: Gateway` with `group: gateway.networking.k8s.io` in the same namespace.
+  // * `kind: GatewayClass` with `group: gateway.networking.k8s.io` in the root namespace.
   // * `kind: Service` with `group: ""` or `group: "core"` in the same namespace. This type is only supported for waypoints.
+  // * `kind: ServiceEntry` with `group: networking.istio.io` in the same namespace.
   //
   // If not set, the policy is applied as defined by the selector.
   // At most one of the selector and targetRefs can be set.

extensions/v1alpha1/wasm.pb.html

@@ -890,7 +890,9 @@ message EnvoyFilter {
   //
   // Currently, the following resource attachment types are supported:
   // * `kind: Gateway` with `group: gateway.networking.k8s.io` in the same namespace.
+  // * `kind: GatewayClass` with `group: gateway.networking.k8s.io` in the root namespace.
   // * `kind: Service` with `""` in the same namespace. This type is only supported for waypoints.
+  // * `kind: ServiceEntry` with `group: networking.istio.io` in the same namespace.
   //
   // If not set, the policy is applied as defined by the selector.
   // At most one of the selector and targetRefs can be set.

extensions/v1alpha1/wasm.proto

@@ -0,0 +1,8 @@
+apiVersion: release-notes/v2
+kind: feature
+area: traffic-management
+issue:
+  - https://github.com/istio/istio/issues/54696
+releaseNotes:
+- |
+  **Removed** CEL validation of group/kind for PolicyTargetReference to enable vendor extensions