Additional Metrics collected and exposed via prometheus (#5414)

This PR refactors the metrics measuring and Prometheus exposing entity in sc-service into its own submodule and extends the parameters it exposes by:

- system load average (over one, five and 15min)
- the TCP connection state of the process (lsof), refs #5304
- number of tokio threads
- number of known forks
- counter for items in each unbounded queue (with internal unbounded channels)
- number of file descriptors opened by this process (*nix only at this point)
- number of system threads (*nix only at this point)

refs #4679

Co-authored-by: Max Inden <mail@max-inden.de>
Co-authored-by: Ashley <ashley.ruglys@gmail.com>

substrate/client/finality-grandpa/src/communication/mod.rs

@@ -58,6 +58,7 @@ use gossip::{
 use sp_finality_grandpa::{
 	AuthorityPair, AuthorityId, AuthoritySignature, SetId as SetIdNumber, RoundNumber,
 };
+use sp_utils::mpsc::TracingUnboundedReceiver;
 
 pub mod gossip;
 mod periodic;
@@ -165,7 +166,7 @@ pub(crate) struct NetworkBridge<B: BlockT, N: Network<B>> {
 	// thus one has to wrap gossip_validator_report_stream with an `Arc` `Mutex`. Given that it is
 	// just an `UnboundedReceiver`, one could also switch to a multi-producer-*multi*-consumer
 	// channel implementation.
-	gossip_validator_report_stream: Arc<Mutex<mpsc::UnboundedReceiver<PeerReport>>>,
+	gossip_validator_report_stream: Arc<Mutex<TracingUnboundedReceiver<PeerReport>>>,
 }
 
 impl<B: BlockT, N: Network<B>> Unpin for NetworkBridge<B, N> {}