Refactor the balances module (#4649)

* Initially scoping out of the problem

* Remove need for exiry in balance locks.

* Remove expiry from locks.

* Remove supefluous balance test

* Amalgamate pieces of balance module

* Split out vesting

* Fix tests

* Fixes for vesting.

* Docs.

* Weight docs.

* Refactor things in terms of set_balances.

* Switch out ED to be free + reserved.

* Remove on_free_balance_zero and some docs.

* Build fixes

* Update frame/vesting/src/lib.rs

Co-Authored-By: Xiliang Chen <xlchen1291@gmail.com>

* Update frame/vesting/src/lib.rs

Co-Authored-By: Xiliang Chen <xlchen1291@gmail.com>

* Migration

* Remove superfluous code.

* Test fixes

* Fix some tests

* Fix repatriate reserve

* Fixes

* Add test for migration

* Final cleanups

* Fix

* Indentation.

* Undo unneeded referencing

* Bump runtime version

* Fixes

Co-authored-by: Xiliang Chen <xlchen1291@gmail.com>

substrate/frame/staking/src/mock.rs

@@ -140,19 +140,16 @@ impl frame_system::Trait for Test {
 	type ModuleToIndex = ();
 }
 parameter_types! {
-	pub const TransferFee: Balance = 0;
 	pub const CreationFee: Balance = 0;
 }
 impl pallet_balances::Trait for Test {
 	type Balance = Balance;
-	type OnFreeBalanceZero = Staking;
-	type OnReapAccount = System;
+	type OnReapAccount = (System, Staking);
 	type OnNewAccount = ();
 	type Event = ();
 	type TransferPayment = ();
 	type DustRemoval = ();
 	type ExistentialDeposit = ExistentialDeposit;
-	type TransferFee = TransferFee;
 	type CreationFee = CreationFee;
 }
 parameter_types! {
@@ -323,7 +320,6 @@ impl ExtBuilder {
 					// This allow us to have a total_payout different from 0.
 					(999, 1_000_000_000_000),
 			],
-			vesting: vec![],
 		}.assimilate_storage(&mut storage);
 
 		let stake_21 = if self.fair { 1000 } else { 2000 };