Add more metrics to prometheus (#5034)

* Add a few things

* Add finality_grandpa_round

* fix fg tests

* Nitpicks

* Nitpicks

* Fix name of prometheus crate

substrate/bin/node-template/node/src/service.rs

@@ -157,6 +157,7 @@ pub fn new_full(config: Configuration<GenesisConfig>)
 			on_exit: service.on_exit(),
 			telemetry_on_connect: Some(service.telemetry_on_connect_stream()),
 			voting_rule: grandpa::VotingRulesBuilder::default().build(),
+			prometheus_registry: service.prometheus_registry()
 		};
 
 		// the GRANDPA voter task is considered infallible, i.e.