pallet_staking: Introduce Additional Account for Inflation Distribution Alongside PBR

[TarekkMA]

New version of #2958, with a simpler design and no storage maps being used

Checklist

• Write tests for the new changes
• Fix/Add all required rustdocs
• Write a migration
• Discuss the possibility of moving to pallet_parameters
  • This would require more refactoring for tests and changing code, so I opted to have this in another PR.
• Write benchmark for the new ext

What does it do?

• Add a new account (Treasury) to have inflation be distributed to along side PBR Parachain Bond Reserve account.
• I kept the old extrinsics of changing PBR account/percentage as is for backward compatibility.

What important points reviewers should know?

• I've wrapped the static array with a struct since it seems like an array on it's own would not work correctly with ts typegen.

Is there something left for follow-up PRs?

• If we will pursuit using pallet parameters with this change, we will need another PR

What alternative implementations were considered?

• StorageMap implemented in this PR: pallet_staking: Introduce Additional Account for Inflation Distribution Alongside PBR #2958

Are there relevant PRs or issues in other repositories (Substrate, Polkadot, Frontier, Cumulus)?

What value does it bring to the blockchain users?

[github-actions]

WASM runtime size check:

Compared to target branch

Moonbase runtime: 2288 KB (no changes) ✅

Moonbeam runtime: 2240 KB (no changes) ✅

Moonriver runtime: 2236 KB (no changes) ✅

Compared to latest release (runtime-3200)

Moonbase runtime: 2288 KB (+328 KB compared to latest release) ⚠️

Moonbeam runtime: 2240 KB (+316 KB compared to latest release) ⚠️

Moonriver runtime: 2236 KB (+312 KB compared to latest release) ⚠️

[github-actions]

Coverage Report

@@                        Coverage Diff                         @@
##           master   tarekkma/staking-add-address-2      +/-   ##
==================================================================
- Coverage   79.18%                           79.12%   -0.06%     
+ Files         299                              300       +1     
+ Lines       87673                            87957     +284     
==================================================================
+ Hits        69419                            69594     +175     
+ Misses      18254                            18363     +109     

Files Changed	Coverage
/pallets/parachain-staking/src/lib.rs	91.79% (+0.05%)	🔼
/pallets/parachain-staking/src/mock.rs	97.70% (+0.07%)	🔼
/pallets/parachain-staking/src/tests.rs	90.85% (-0.51%)	🔽
/pallets/parachain-staking/src/types.rs	78.05% (-0.27%)	🔽
/pallets/parachain-staking/src/weights.rs	38.35% (-0.49%)	🔽
/runtime/common/src/migrations.rs	72.09% (-0.24%)	🔽
/runtime/common/src/weights/pallet_parachain_staking.rs	19.59% (-0.27%)	🔽

Coverage generated Mon Oct 7 08:34:30 UTC 2024

[librelois]

Some minor comments, but overall it's good 👍