Add ERC-7969 compliant DKIMRegistry

[ernestognw]

See https://eip.tools/eip/7969

[0xknon]

Suggested change

	abstract contract DKIMRegistry is IDKIMRegistry {
	contract DKIMRegistry is IDKIMRegistry {

[ernestognw]

Hi @0xknon, we generally mark contracts as abstract to make it clear that it's not our intention for people deploy them directly. Note it's missing the public setKeyHash, setKeyHashes and revokeKeyHash functions that require access control.

Alternatively, we can define this functions within the contract but add a modifier with an internal virtual _checkKeyHashUpdate:

abstract contract MyDKIMRegistry is DKIMRegistry, Ownable {
    modifier onlyKeyHashUpdater() {
        _checkKeyHashUpdater();
        _;
    }

    function setKeyHash(bytes32 domainHash, bytes32 keyHash) public onlyKeyHashUpdater {
        _setKeyHash(domainHash, keyHash);
    }

    function setKeyHashes(bytes32 domainHash, bytes32[] memory keyHashes) public onlyKeyHashUpdater {
        _setKeyHashes(domainHash, keyHashes);
    }

    function revokeKeyHash(bytes32 domainHash, bytes32 keyHash) public onlyKeyHashUpdater {
        _revokeKeyHash(domainHash, keyHash);
    }

   ...

    function _checkKeyHashUpdater() internal virtual view;
}

It would be still abstract, but maybe closer to a straightforward deployment. wdyt?