Integrate GRPCRoute into NIMService

[shengnuo]

This MR adds integrates NIMServices with GRPCRoute.

• GRPCRoutes can be enabled via .spec.router.gateway.grpcRoutesEnabled

  router:
    gateway:
      namespace: nemo
      name: istio-gateway
      grpcRoutesEnabled: true
    hostDomainName: demo.nvidia.example.com

• GRPC Port is specified under .spec.expose.service.grpcPort. If it's not specified, the default 50051 port is used.
• If HTTPRoute is enabled along with GRPCRoute, then HTTPRoute and GRPCRoute objects will be created with the same hostname specified under .spec.router.hostname

Sample Istio Gateway (HTTP + gRPC on same hostname)

apiVersion: gateway.networking.k8s.io/v1
kind: Gateway
metadata:
  name: istio-gateway
  namespace: nemo
spec:
  gatewayClassName: istio
  listeners:
  - allowedRoutes:
      namespaces:
        from: All
      kinds:
      - kind: HTTPRoute
    hostname: riva-tts.nemo.demo.nvidia.example.com
    name: http
    port: 80
    protocol: HTTP
  - allowedRoutes:
      namespaces:
        from: All
      kinds:
      - kind: GRPCRoute
    hostname: riva-tts.nemo.demo.nvidia.example.com
    name: grpc
    port: 50051
    protocol: HTTP

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[shivamerla]

Looks good! thanks @shengnuo Now API looks much better.

[shivamerla]

/ok to test 4d5c504

[mkhaas]

Suggested change

	hostDomainName: demo.nvidia.example.com
	hostDomainName: demo.example.nvidia.com

[shivamerla]

/ok to test 599b83e