Mesh 2149/staking-pallet-update-part-1

[HenriqueNogara]

This PR updates our staking pallet to use the new macros. This also makes our code easier to compare to the substrate code.

Most relevant changes:

• Adds two new associated types (MaxUnlockingChunksand MaxNominations);

• All Polymesh custom types were moved to pallets/staking/src/types.rs;

• All pallet definitions were moved to pallets/staking/src/pallet/mod.rs, this includes Config, Storage, Event, Error, Hooks and Call;

• All functions that are not extrinsics were moved to pallets/staking/src/pallet/impls.rs;

• The StakingLedger struct is now generic over T: Config;

• The Nominations struct is now generic over T: Config, and Nominations::targets is now a BoundedVec not a Vec;

• The inner function slashable_balance_of_fn was renamed weight_of_fn;

• The inner function collect_exposure was renamed collect_exposures;

• Adds two error variants: BoundNotMet, TooManyNominators;

• Note: on_runtime_upgrade was removed;

  changelog

new features

modified external API

• Adds two error variants: BoundNotMet, TooManyNominators to the staking pallet Error;