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/import.rs

@@ -18,11 +18,11 @@ use std::{sync::Arc, collections::HashMap};
 
 use log::{debug, trace, info};
 use parity_scale_codec::Encode;
-use futures::channel::mpsc;
 use parking_lot::RwLockWriteGuard;
 
 use sp_blockchain::{BlockStatus, well_known_cache_keys};
 use sc_client_api::{backend::Backend, utils::is_descendent_of};
+use sp_utils::mpsc::TracingUnboundedSender;
 use sp_api::{TransactionFor};
 
 use sp_consensus::{
@@ -57,7 +57,7 @@ pub struct GrandpaBlockImport<Backend, Block: BlockT, Client, SC> {
 	inner: Arc<Client>,
 	select_chain: SC,
 	authority_set: SharedAuthoritySet<Block::Hash, NumberFor<Block>>,
-	send_voter_commands: mpsc::UnboundedSender<VoterCommand<Block::Hash, NumberFor<Block>>>,
+	send_voter_commands: TracingUnboundedSender<VoterCommand<Block::Hash, NumberFor<Block>>>,
 	consensus_changes: SharedConsensusChanges<Block::Hash, NumberFor<Block>>,
 	authority_set_hard_forks: HashMap<Block::Hash, PendingChange<Block::Hash, NumberFor<Block>>>,
 	_phantom: PhantomData<Backend>,
@@ -536,7 +536,7 @@ impl<Backend, Block: BlockT, Client, SC> GrandpaBlockImport<Backend, Block, Clie
 		inner: Arc<Client>,
 		select_chain: SC,
 		authority_set: SharedAuthoritySet<Block::Hash, NumberFor<Block>>,
-		send_voter_commands: mpsc::UnboundedSender<VoterCommand<Block::Hash, NumberFor<Block>>>,
+		send_voter_commands: TracingUnboundedSender<VoterCommand<Block::Hash, NumberFor<Block>>>,
 		consensus_changes: SharedConsensusChanges<Block::Hash, NumberFor<Block>>,
 		authority_set_hard_forks: Vec<(SetId, PendingChange<Block::Hash, NumberFor<Block>>)>,
 	) -> GrandpaBlockImport<Backend, Block, Client, SC> {