feat: add hgctl dashboard support (#552)

Signed-off-by: bitliu <bitliu@tencent.com>

pkg/cmd/hgctl/kubernetes/port-forwarder.go

@@ -48,6 +48,9 @@ type PortForwarder interface {
 
 	// Address returns the address of the local forwarded address.
 	Address() string
+
+	// WaitForStop blocks until connection closed (e.g. control-C interrupt)
+	WaitForStop()
 }
 
 var _ PortForwarder = &localForwarder{}
@@ -153,3 +156,7 @@ func (f *localForwarder) Stop() {
 func (f *localForwarder) Address() string {
 	return fmt.Sprintf("%s:%d", DefaultLocalAddress, f.localPort)
 }
+
+func (f *localForwarder) WaitForStop() {
+	<-f.stopCh
+}