Polkadot <> Kusama relayers (#1122)

* relay headers between Kusama and Polkadot

* relay messages between Kusama and Polkadot

* complex Kusama <> Polkadot relayer

* expose relayer_fund_account_id from messages pallet

* create relayers fund accounts on Kusama/Polkadot + some more fixes

* fmt

* fix compilation

* compilation + clippy

* compilation

* MAXIMAL_BALANCE_DECREASE_PER_DAY for K<>P header relays

* fmt

* deduplicate tests

* Update modules/messages/src/lib.rs

Co-authored-by: Tomasz Drwięga <tomusdrw@users.noreply.github.com>

* extract storage_parameter_key function

* other grumbles

* fix

* fmt

Co-authored-by: Tomasz Drwięga <tomusdrw@users.noreply.github.com>

bridges/relays/bin-substrate/src/cli/init_bridge.rs

@@ -46,6 +46,8 @@ pub enum InitBridgeName {
 	WestendToMillau,
 	RococoToWococo,
 	WococoToRococo,
+	KusamaToPolkadot,
+	PolkadotToKusama,
 }
 
 macro_rules! select_bridge {
@@ -127,6 +129,34 @@ macro_rules! select_bridge {
 					)
 				}
 
+				$generic
+			}
+			InitBridgeName::KusamaToPolkadot => {
+				type Source = relay_kusama_client::Kusama;
+				type Target = relay_polkadot_client::Polkadot;
+
+				fn encode_init_bridge(
+					init_data: InitializationData<<Source as ChainBase>::Header>,
+				) -> <Target as Chain>::Call {
+					relay_polkadot_client::runtime::Call::BridgeKusamaGrandpa(
+						relay_polkadot_client::runtime::BridgeKusamaGrandpaCall::initialize(init_data),
+					)
+				}
+
+				$generic
+			}
+			InitBridgeName::PolkadotToKusama => {
+				type Source = relay_polkadot_client::Polkadot;
+				type Target = relay_kusama_client::Kusama;
+
+				fn encode_init_bridge(
+					init_data: InitializationData<<Source as ChainBase>::Header>,
+				) -> <Target as Chain>::Call {
+					relay_kusama_client::runtime::Call::BridgePolkadotGrandpa(
+						relay_kusama_client::runtime::BridgePolkadotGrandpaCall::initialize(init_data),
+					)
+				}
+
 				$generic
 			}
 		}