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-substrate/src/chain.rs

@@ -18,8 +18,8 @@ use crate::calls::UtilityCall;
 
 use bp_messages::MessageNonce;
 use bp_runtime::{
-	Chain as ChainBase, EncodedOrDecodedCall, HashOf, Parachain as ParachainBase, TransactionEra,
-	TransactionEraOf, UnderlyingChainProvider,
+	Chain as ChainBase, ChainId, EncodedOrDecodedCall, HashOf, Parachain as ParachainBase,
+	TransactionEra, TransactionEraOf, UnderlyingChainProvider,
 };
 use codec::{Codec, Encode};
 use jsonrpsee::core::{DeserializeOwned, Serialize};
@@ -35,6 +35,8 @@ use std::{fmt::Debug, time::Duration};
 
 /// Substrate-based chain from minimal relay-client point of view.
 pub trait Chain: ChainBase + Clone {
+	/// Chain id.
+	const ID: ChainId;
 	/// Chain name.
 	const NAME: &'static str;
 	/// Identifier of the basic token of the chain (if applicable).

bridges/relays/client-substrate/src/test_chain.rs

@@ -22,6 +22,7 @@
 #![cfg(any(feature = "test-helpers", test))]
 
 use crate::{Chain, ChainWithBalances};
+use bp_runtime::ChainId;
 use frame_support::weights::Weight;
 use std::time::Duration;
 
@@ -50,6 +51,7 @@ impl bp_runtime::Chain for TestChain {
 }
 
 impl Chain for TestChain {
+	const ID: ChainId = *b"test";
 	const NAME: &'static str = "Test";
 	const TOKEN_ID: Option<&'static str> = None;
 	const BEST_FINALIZED_HEADER_ID_METHOD: &'static str = "TestMethod";