test(Bundler): add coverage for Ownable2Step, better fuzzing for trustedBatchRegister

[varunsrin]

Motivation

Improves coverage for core Bundler functionality

Change Summary

• added coverage for Ownable2Step
• added better fuzzing for trustedBatchRegister

Merge Checklist

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

• [x] The PR title adheres to the conventional commits standard
• [x] The PR has been tagged with change type label(s) (i.e. documentation, feature, bugfix, or chore)
• [x] The PR's changes adhere to all the requirements in the contribution guidelines
• [x] This PR does not require changes to the Farcaster protocol

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PR-Codex overview

Focus of this PR:

This PR focuses on adding ownership transfer functionality to the Bundler contract.

Detailed summary:

• Added OwnershipTransferred event.
• Added Rent event.
• Modified the testFuzzTrustedBatchRegister function to take the number of registrations as a parameter.
• Updated the testFuzzTrustedBatchRegister function to use a loop for batch registration.
• Added testFuzzTransferOwnership function to test ownership transfer functionality.
• Added testFuzzCannotTransferOwnershipUnlessOwner function to test restriction on ownership transfer.
• Added testFuzzAcceptOwnership function to test ownership acceptance functionality.
• Added testFuzzCannotAcceptOwnershipUnlessPendingOwner function to test restriction on ownership acceptance.

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[github-actions[bot]]

Coverage after merging varunsrin/bundler-test-coverage into main will be

98.77%

Coverage Report

File	Stmts	Branches	Funcs	Lines	Uncovered Lines
src
Bundler.sol	94.12%	83.33%	100%	100%	124, 126
FnameResolver.sol	96.30%	75%	100%	100%	121
IdRegistry.sol	97.30%	100%	92.31%	97.44%	315
StorageRent.sol	98.82%	98.39%	100%	98.88%	463, 465