Define ss58 prefix inside the runtime (#7810)

* Add SS58Prefix type to the frame_system config trait

* Remove unused chain_id runtime interface

Author: athei

src/tests.rs

@@ -130,6 +130,7 @@ impl frame_system::Config for Test {
 	type OnNewAccount = ();
 	type OnKilledAccount = ();
 	type SystemWeightInfo = ();
+	type SS58Prefix = ();
 }
 impl pallet_balances::Config for Test {
 	type MaxLocks = ();