Relayers pallet: extend payment source id (#1907)

* Add Chain::ID const

* Relayers pallet: extend payment source id

* Addressed code review comments

* Fix benchmarks

* Fix dashboards

* Renamings

* Fix compilation

bridges/relays/client-rococo/Cargo.toml

@@ -12,6 +12,7 @@ relay-utils = { path = "../utils" }
 # Bridge dependencies
 
 bp-rococo = { path = "../../primitives/chain-rococo" }
+bp-runtime = { path = "../../primitives/runtime" }
 
 # Substrate Dependencies
 

bridges/relays/client-rococo/src/lib.rs

@@ -16,6 +16,7 @@
 
 //! Types used to connect to the Rococo-Substrate chain.
 
+use bp_runtime::ChainId;
 use relay_substrate_client::{Chain, ChainWithBalances, RelayChain, UnderlyingChainProvider};
 use sp_core::storage::StorageKey;
 use std::time::Duration;
@@ -35,6 +36,7 @@ impl UnderlyingChainProvider for Rococo {
 }
 
 impl Chain for Rococo {
+	const ID: ChainId = bp_runtime::ROCOCO_CHAIN_ID;
 	const NAME: &'static str = "Rococo";
 	const TOKEN_ID: Option<&'static str> = None;
 	const BEST_FINALIZED_HEADER_ID_METHOD: &'static str =