Missing events for critical operations

[code423n4]

Handle

WatchPug

Vulnerability details

Across the contracts, there are certain critical operations that change critical values that affect the users of the protocol.

It's a best practice for these setter functions to emit events to record these changes on-chain for off-chain monitors/tools/interfaces to register the updates and react if necessary.

Instances include:

https://github.com/code-423n4/2021-11-yaxis/blob/146febcb61ae7fe20b0920849c4f4bbe111c6ba7/contracts/v3/alchemix/AlToken.sol#L93-L95

function setBlacklist(address _toBlacklist) external onlySentinel {
        blacklist[_toBlacklist] = true;
    }

https://github.com/code-423n4/2021-11-yaxis/blob/146febcb61ae7fe20b0920849c4f4bbe111c6ba7/contracts/v3/alchemix/AlToken.sol#L78-L80

function setWhitelist(address _toWhitelist, bool _state) external onlyAdmin {
        whiteList[_toWhitelist] = _state;
    }

https://github.com/code-423n4/2021-11-yaxis/blob/146febcb61ae7fe20b0920849c4f4bbe111c6ba7/contracts/v3/alchemix/AlToken.sol#L107-L109

function setCeiling(address _toSetCeiling, uint256 _ceiling) external onlyAdmin {
        ceiling[_toSetCeiling] = _ceiling;
    }

[Xuefeng-Zhu]

#34