Add prometheus registry to transaction pool, with couple of initial metrics (#5657)

* make new contructor

* add metrics to txpool

* fix review

* fix doc comment

* change to counters

* Update client/transaction-pool/src/metrics.rs

Co-Authored-By: Max Inden <mail@max-inden.de>

* Update client/transaction-pool/src/metrics.rs

Co-Authored-By: Max Inden <mail@max-inden.de>

* Update client/transaction-pool/src/metrics.rs

Co-Authored-By: Max Inden <mail@max-inden.de>

* Update client/transaction-pool/src/lib.rs

Co-Authored-By: Max Inden <mail@max-inden.de>

* Update client/transaction-pool/src/lib.rs

Co-Authored-By: Max Inden <mail@max-inden.de>

* use dedicated wrapper

Co-authored-by: Max Inden <mail@max-inden.de>

substrate/client/service/src/builder.rs

@@ -53,6 +53,7 @@ use wasm_timer::SystemTime;
 use sc_telemetry::{telemetry, SUBSTRATE_INFO};
 use sp_transaction_pool::{MaintainedTransactionPool, ChainEvent};
 use sp_blockchain;
+use prometheus_endpoint::Registry as PrometheusRegistry;
 
 pub type BackgroundTask = Pin<Box<dyn Future<Output=()> + Send>>;
 
@@ -585,6 +586,7 @@ impl<TBl, TRtApi, TCl, TFchr, TSc, TImpQu, TFprb, TFpp, TExPool, TRpc, Backend>
 			sc_transaction_pool::txpool::Options,
 			Arc<TCl>,
 			Option<TFchr>,
+			Option<&PrometheusRegistry>,
 		) -> Result<(UExPool, Option<BackgroundTask>), Error>
 	) -> Result<ServiceBuilder<TBl, TRtApi, TCl, TFchr, TSc, TImpQu, TFprb, TFpp,
 		UExPool, TRpc, Backend>, Error>
@@ -593,6 +595,7 @@ impl<TBl, TRtApi, TCl, TFchr, TSc, TImpQu, TFprb, TFpp, TExPool, TRpc, Backend>
 			self.config.transaction_pool.clone(),
 			self.client.clone(),
 			self.fetcher.clone(),
+			self.config.prometheus_config.as_ref().map(|config| &config.registry),
 		)?;
 
 		if let Some(background_task) = background_task{

substrate/client/service/src/lib.rs

@@ -696,6 +696,7 @@ mod tests {
 		let pool = Arc::new(BasicPool::new(
 			Default::default(),
 			Arc::new(FullChainApi::new(client.clone())),
+			None,
 		).0);
 		let source = sp_runtime::transaction_validity::TransactionSource::External;
 		let best = longest_chain.best_chain().unwrap();