Network bridge metrics (#2818)

* add metrics (unused) to network bridge

* fix test compilation

* trigger metrics messages

* add some more metrics

* track sent and received notifications

* restore metrics import

* integrate into service

* Update node/network/bridge/src/lib.rs

Co-authored-by: Andronik Ordian <write@reusable.software>

* Update node/network/bridge/src/lib.rs

Co-authored-by: Andronik Ordian <write@reusable.software>

Co-authored-by: Andronik Ordian <write@reusable.software>

polkadot/node/service/src/lib.rs

@@ -548,6 +548,7 @@ where
 			authority_discovery,
 			request_multiplexer,
 			Box::new(network_service.clone()),
+			Metrics::register(registry)?,
 		),
 		provisioner: ProvisionerSubsystem::new(
 			spawner.clone(),