Define ss58 prefix inside the runtime (#7810)

* Add SS58Prefix type to the frame_system config trait

* Remove unused chain_id runtime interface

substrate/bin/node-template/pallets/template/src/mock.rs

@@ -16,6 +16,7 @@ impl_outer_origin! {
 pub struct Test;
 parameter_types! {
 	pub const BlockHashCount: u64 = 250;
+	pub const SS58Prefix: u8 = 42;
 }
 
 impl system::Config for Test {
@@ -40,6 +41,7 @@ impl system::Config for Test {
 	type OnNewAccount = ();
 	type OnKilledAccount = ();
 	type SystemWeightInfo = ();
+	type SS58Prefix = SS58Prefix;
 }
 
 impl Config for Test {