remove OnStakerSlash replace with OnStakingEvents (#14527)

* remove 'OnStakerSlash', replace with 'OnStakingEvents'

* fix other features in pallets

* small fixes

* fix docs

* fix docs

* fix docs

* Update primitives/staking/src/lib.rs

Co-authored-by: Gonçalo Pestana <g6pestana@gmail.com>

---------

Co-authored-by: Gonçalo Pestana <g6pestana@gmail.com>

substrate/frame/staking/src/pallet/mod.rs

@@ -24,7 +24,7 @@ use frame_support::{
 	dispatch::Codec,
 	pallet_prelude::*,
 	traits::{
-		Currency, CurrencyToVote, Defensive, DefensiveResult, DefensiveSaturating, EnsureOrigin,
+		Currency, Defensive, DefensiveResult, DefensiveSaturating, EnsureOrigin,
 		EstimateNextNewSession, Get, LockIdentifier, LockableCurrency, OnUnbalanced, TryCollect,
 		UnixTime,
 	},
@@ -113,7 +113,7 @@ pub mod pallet {
 		/// in 128.
 		/// Consequently, the backward convert is used convert the u128s from sp-elections back to a
 		/// [`BalanceOf`].
-		type CurrencyToVote: CurrencyToVote<BalanceOf<Self>>;
+		type CurrencyToVote: sp_staking::currency_to_vote::CurrencyToVote<BalanceOf<Self>>;
 
 		/// Something that provides the election functionality.
 		type ElectionProvider: ElectionProvider<
@@ -261,9 +261,11 @@ pub mod pallet {
 		#[pallet::constant]
 		type MaxUnlockingChunks: Get<u32>;
 
-		/// A hook called when any staker is slashed. Mostly likely this can be a no-op unless
-		/// other pallets exist that are affected by slashing per-staker.
-		type OnStakerSlash: sp_staking::OnStakerSlash<Self::AccountId, BalanceOf<Self>>;
+		/// Something that listens to staking updates and performs actions based on the data it
+		/// receives.
+		///
+		/// WARNING: this only reports slashing events for the time being.
+		type EventListeners: sp_staking::OnStakingUpdate<Self::AccountId, BalanceOf<Self>>;
 
 		/// Some parameters of the benchmarking.
 		type BenchmarkingConfig: BenchmarkingConfig;