feat: add (re)delegation getters (backport cosmos#11596) (cosmos#11615)

* feat: add (re)delegation getters (cosmos#11596)

### Description

This PR adds general helper functions to the `x/staking` module that are used in the Evmos `x/vesting` module and originated from Agoric's custom staking module implementation https://github.com/agoric-labs/cosmos-sdk/blob/4085-true-vesting/x/staking/keeper/delegation.go.

- `GetDelegatorUnbonding`
- `GetDelegatorBonded`
- `IterateDelegatorUnbondingDelegations`
- `IterateDelegatorDelegations`
- `IterateDelegatorRedelegations`

(cherry picked from commit b8270fc)

# Conflicts:
#	CHANGELOG.md
#	x/staking/keeper/delegation.go

* fix RemoveDelegation method conflict

* fix CHANGELOG conflict

* add new PR in CHANGELOG

Co-authored-by: Daniel Burckhardt <daniel.m.burckhardt@gmail.com>

CHANGELOG.md

@@ -60,16 +60,17 @@ Ref: https://keepachangelog.com/en/1.0.0/
 * [\#11124](https://github.com/cosmos/cosmos-sdk/pull/11124) Add `GetAllVersions` to application store
 * (x/auth) [\#10880](https://github.com/cosmos/cosmos-sdk/pull/10880) Added a new query to the tx query service that returns a block with transactions fully decoded.
 * [#11314](https://github.com/cosmos/cosmos-sdk/pull/11314) Add state rollback command.
+* (x/staking) [\#11596](https://github.com/cosmos/cosmos-sdk/pull/11596) Add (re)delegation getters
 
 ### Bug Fixes
 
 * [\#11354](https://github.com/cosmos/cosmos-sdk/pull/11355) Added missing pagination flag for `bank q total` query.
-* [\#11197](https://github.com/cosmos/cosmos-sdk/pull/11197) Signing with multisig now works with multisig address which is not in the keyring. 
+* [\#11197](https://github.com/cosmos/cosmos-sdk/pull/11197) Signing with multisig now works with multisig address which is not in the keyring.
 * (client) [\#11283](https://github.com/cosmos/cosmos-sdk/issues/11283) Support multiple keys for tx simulation and setting automatic gas for txs.
 * (store) [\#11177](https://github.com/cosmos/cosmos-sdk/pull/11177) Update the prune `everything` strategy to store the last two heights.
 * (store) [\#11117](https://github.com/cosmos/cosmos-sdk/pull/11117) Fix data race in store trace component
 * (x/authz) [\#11252](https://github.com/cosmos/cosmos-sdk/pull/11252) Allow insufficient funds error for authz simulation
-* (crypto) [\#11298](https://github.com/cosmos/cosmos-sdk/pull/11298) Fix cgo secp signature verification and update libscep256k1 library. 
+* (crypto) [\#11298](https://github.com/cosmos/cosmos-sdk/pull/11298) Fix cgo secp signature verification and update libscep256k1 library.
 
 ### Improvements
 
@@ -124,7 +125,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 
 ### Bug Fixes
 
-* (std/codec) [/#10595](https://github.com/cosmos/cosmos-sdk/pull/10595) Add evidence to std/codec to be able to decode evidence in client interactions. 
+* (std/codec) [/#10595](https://github.com/cosmos/cosmos-sdk/pull/10595) Add evidence to std/codec to be able to decode evidence in client interactions.
 * (types) [\#9627](https://github.com/cosmos/cosmos-sdk/pull/9627) Fix nil pointer panic on `NewBigIntFromInt`.
 * [#10725](https://github.com/cosmos/cosmos-sdk/pull/10725) populate `ctx.ConsensusParams` for begin/end blockers.
 * [\#9829](https://github.com/cosmos/cosmos-sdk/pull/9829) Fixed Coin denom sorting not being checked during `Balance.Validate` check. Refactored the Validation logic to use `Coins.Validate` for `Balance.Coins`
@@ -134,7 +135,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 
 ### Improvements
 
-* (baseapp) [\#10631](https://github.com/cosmos/cosmos-sdk/pull/10631)  Emit ante events even for the failed txs. 
+* (baseapp) [\#10631](https://github.com/cosmos/cosmos-sdk/pull/10631)  Emit ante events even for the failed txs.
 
 ### Features