feat: batch credit tiers

[horsefacts]

Motivation

Batch credit for existing tier payments without token transfer.

Change Summary

• Reuse Migration abstract contract
• Add batchCreditTier to credit tier without payment
• Add sweepERC20 to rescue ERC20 balance

Merge Checklist

Choose all relevant options below by adding an x now or at any time before submitting for review

• The PR title adheres to the conventional commits standard
• The PR has been tagged with change type label(s) (i.e. documentation, feature, bugfix, or chore)
• The PR's changes adhere to all the requirements in the contribution guidelines
• All commits have been signed

---

PR-Codex overview

This PR enhances the IMigration interface and related contracts, introducing a migration mechanism and improving tier management. It also updates test cases to ensure proper functionality of the new features.

Detailed summary

• IMigration now extends IGuardians.
• ITierRegistry extends IMigration.
• Added batchCreditTier function in ITierRegistry.
• Introduced SweepToken event in ITierRegistry.
• Updated TierRegistry constructor to accept migrator address.
• Modified pause and unpause functions to sweepToken.
• Updated test cases to cover new migration and batch credit functionalities.

The following files were skipped due to too many changes: .gas-snapshot

✨ Ask PR-Codex anything about this PR by commenting with /codex {your question}

[github-actions]

Coverage after merging horsefacts/tier-batch-credit into main will be

100.00%

Coverage Report

File	Stmts	Branches	Funcs	Lines	Uncovered Lines
src
Bundler.sol	100%	100%	100%	100%
BundlerV1.sol	100%	100%	100%	100%
FnameResolver.sol	100%	100%	100%	100%
IdGateway.sol	100%	100%	100%	100%
IdRegistry.sol	100%	100%	100%	100%
KeyGateway.sol	100%	100%	100%	100%
KeyRegistry.sol	100%	100%	100%	100%
RecoveryProxy.sol	100%	100%	100%	100%
StorageRegistry.sol	100%	100%	100%	100%
TierRegistry.sol	100%	100%	100%	100%
src/abstract
EIP712.sol	100%	100%	100%	100%
Guardians.sol	100%	100%	100%	100%
Migration.sol	100%	100%	100%	100%
Nonces.sol	100%	100%	100%	100%
Signatures.sol	100%	100%	100%	100%
src/validators
SignedKeyRequestValidator.sol	100%	100%	100%	100%