ReferenceGrants are ignored by GRPCRoute

[kate-osborn]

Describe the bug
If a GRPCRoute references a Service in a different namespace and a ReferenceGrant exists permitting this cross-namespace reference, the reference is incorrectly rejected.

To Reproduce
Steps to reproduce the behavior:

Apply the following resources:

apiVersion: gateway.networking.k8s.io/v1beta1
kind: ReferenceGrant
metadata:
  name: permit-grpcroute-to-test-services
  namespace: test
spec:
  to:
  - group: ""
    kind: Service
  from:
  - group: gateway.networking.k8s.io
    kind: GRPCRoute
    namespace: default
---
apiVersion: gateway.networking.k8s.io/v1
kind: Gateway
metadata:
  name: same-namespace
spec:
  gatewayClassName: nginx
  listeners:
  - name: http
    port: 80
    protocol: HTTP
    allowedRoutes:
      namespaces:
        from: Same
---
apiVersion: gateway.networking.k8s.io/v1
kind: GRPCRoute
metadata:
  name: exact-matching
spec:
  parentRefs:
  - name: same-namespace
  rules:
  - matches:
    - method:
        service: helloworld.Greeter
        method: SayHello
    backendRefs:
    - name: grpc-infra-backend-v1
      namespace: test
      port: 8080
---
apiVersion: v1
kind: Service
metadata:
  name: grpc-infra-backend-v1
  namespace: test
spec:
  selector:
    app: grpc-infra-backend-v1
  ports:
  - protocol: TCP
    port: 8080
    targetPort: 50051
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: grpc-infra-backend-v1
  namespace: test
  labels:
    app: grpc-infra-backend-v1
spec:
  replicas: 1
  selector:
    matchLabels:
      app: grpc-infra-backend-v1
  template:
    metadata:
      labels:
        app: grpc-infra-backend-v1
    spec:
      containers:
      - name: grpc-infra-backend-v1
        image: ghcr.io/nginxinc/kic-test-grpc-server:0.2.1
        env:
        - name: POD_NAME
          valueFrom:
            fieldRef:
              fieldPath: metadata.name
        resources:
          requests:
            cpu: 10m

Describe the GRPCRoute:

kubectl describe grpcroute

See the error condition for ResolvedRefs:

  Last Transition Time:  2024-08-06T15:38:00Z
  Message:               Backend ref to Service test/grpc-infra-backend-v1 not permitted by any ReferenceGrant
  Observed Generation:   1
  Reason:                RefNotPermitted
  Status:                False
  Type:                  ResolvedRefs
Controller Name:         gateway.nginx.org/nginx-gateway-controller

Expected behavior
ResolvedRefs condition on GRPCRoute should be True

Your environment

• Version of the NGINX Gateway Fabric - edge f24ab6f

Additional context
Add any other context about the problem here. Any log files you want to share.