🗞️ Add MintBurnOFTAdapter.sol to oft-evm package

[St0rmBr3w]

In this PR:

This PR introduces the audited MintBurnOFTAdapter example to the oft-evm package and updates the relevant tests to ensure its proper functionality. The MintBurnOFTAdapter provides a generic solution for integrating tokens that utilize mint and burn mechanisms into the LayerZero Omnichain Fungible Token (OFT) framework.

Key Changes:

Added MintBurnOFTAdapter Contract:

• Implemented an abstract contract MintBurnOFTAdapter that inherits from OFTCore.
• Provides implementations for the _debit and _credit functions using mint and burn operations via a IMintableBurnable interface.
• Designed to work with tokens that have mintable and burnable capabilities, facilitating cross-chain transfers without the need for token approvals.

Updated Tests:

• Added new test cases to cover the functionality of the MintBurnOFTAdapter.
• Ensured existing tests are compatible and pass with the introduction of the new adapter.

Discussion Points:

Discrepancies Between Generic Version and FRAX Implementation:

• There are noticeable differences between this generic version of the MintBurnOFTAdapter and the specific implementation used by FRAX. Notably:

  • The FRAX implementation uses a direct OFTMinterBurner, whereas the generic version references an ElevatedMinterBurnerMock.
  • Different ERC20 tokens have varying implementations of the _mint and _burn functions, often with guarded access or additional logic. Tokens with unique or restricted mint/burn functions may require custom implementations or extensions of the adapter.

Developers should have clear guidelines on how to adapt the MintBurnOFTAdapter to their specific token logic.

To-Do:

• Unify Around Intended Developer Experience

• Decide whether to maintain a generic adapter or create specialized versions for different token types.

• Consider providing base contracts that can be extended for tokens with custom mint/burn logic.

[shankars99]

LGTM!