Migrate pallet-staking to pallet attribute macro (#9083)

* Migrate staking pallet to pallet attribute macro.

* HistoryDepth default value.

* Make all calls public.

* Update frame/staking/src/lib.rs

* remove externalities again

* Update lib.rs

Co-authored-by: Shawn Tabrizi <shawntabrizi@gmail.com>

substrate/frame/babe/src/mock.rs

@@ -28,7 +28,7 @@ use sp_runtime::{
 use frame_system::InitKind;
 use frame_support::{
 	parameter_types,
-	traits::{KeyOwnerProofSystem, OnInitialize},
+	traits::{KeyOwnerProofSystem, OnInitialize, GenesisBuild},
 };
 use sp_io;
 use sp_core::{H256, U256, crypto::{IsWrappedBy, KeyTypeId, Pair}};