Add Service name references for Ingress v1

Since Kubernetes v1.19, Ingress networking.k8s.io/v1 has two more Server name references.
- https://kubernetes.io/docs/concepts/services-networking/ingress/#the-ingress-resource
- https://kubernetes.io/docs/setup/release/notes/

api/konfig/builtinpluginconsts/namereference.go

@@ -267,6 +267,10 @@ nameReference:
     kind: Ingress
   - path: spec/backend/serviceName
     kind: Ingress
+  - path: spec/rules/http/paths/backend/service/name
+    kind: Ingress
+  - path: spec/defaultBackend/service/name
+    kind: Ingress
   - path: spec/service/name
     kind: APIService
     group: apiregistration.k8s.io