Refactor message relay helpers (#1234)

* refactor message relay helpers

* single standalone_metrics function

* fixed tests

* clippy + fmt

* removed commented code

* add calls tracing

* fix spelling

* cargo fmt

* -commented code

* fix build again

* post-merge build fix

* clippy + fmt

bridges/bin/millau/node/src/service.rs

@@ -66,6 +66,7 @@ type FullClient =
 type FullBackend = sc_service::TFullBackend<Block>;
 type FullSelectChain = sc_consensus::LongestChain<FullBackend, Block>;
 
+#[allow(clippy::type_complexity)]
 pub fn new_partial(
 	config: &Configuration,
 ) -> Result<
@@ -89,7 +90,7 @@ pub fn new_partial(
 	ServiceError,
 > {
 	if config.keystore_remote.is_some() {
-		return Err(ServiceError::Other(format!("Remote Keystores are not supported.")))
+		return Err(ServiceError::Other("Remote Keystores are not supported.".into()))
 	}
 
 	let telemetry = config
@@ -111,7 +112,7 @@ pub fn new_partial(
 
 	let (client, backend, keystore_container, task_manager) =
 		sc_service::new_full_parts::<Block, RuntimeApi, _>(
-			&config,
+			config,
 			telemetry.as_ref().map(|(_, telemetry)| telemetry.handle()),
 			executor,
 		)?;
@@ -178,7 +179,7 @@ pub fn new_partial(
 	})
 }
 
-fn remote_keystore(_url: &String) -> Result<Arc<LocalKeystore>, &'static str> {
+fn remote_keystore(_url: &str) -> Result<Arc<LocalKeystore>, &'static str> {
 	// FIXME: here would the concrete keystore be built,
 	//        must return a concrete type (NOT `LocalKeystore`) that
 	//        implements `CryptoStore` and `SyncCryptoStore`