Vulnerability: USDO's MSG_TAP_EXERCISE compose messages where exercised options must be withdrawn to another chain will always fail due to wrongly requiring sendParam's to address to be whitelisted in the Cluster
Severity: medium

Description:
Wrongly checking for the sendParam's `to` address `to` be whitelisted when bridging exercised options will make such calls always fail.\\nOne of the compose messages allowed in USDO is `MSG_TAP_EXERCISE`. This type of message will trigger UsdoOptionReceiverModule's `exerciseOptionsReceiver()` function, which allows users to exercise their options and obtain the corresponding exercised tapOFTs.\\nUsers can choose to obtain their tapOFTs in the chain where `exerciseOptionsReceiver()` is being executed, or they can choose to send a message to a destination chain of their choice. If users decide to bridge the exercised option, the `lzSendParams` fields contained in the `ExerciseOptionsMsg` struct decoded from the `_data` passed as parameter in `exerciseOptionsReceiver()` should be filled with the corresponding data to perform the cross-chain call.\\nThe problem is that the `exerciseOptionsReceiver()` performs an unnecessary validation that requires the `to` parameter inside the `lzSendParams` `to` be whitelisted in the protocol's cluster:\\n```\\n// UsdoOptionReceiverModule.sol\\n\\nfunction exerciseOptionsReceiver(address srcChainSender, bytes memory _data) public payable {\\n        // Decode received message.\\n        ExerciseOptionsMsg memory msg_ = UsdoMsgCodec.decodeExerciseOptionsMsg(_data);\\n  \\n        _checkWhitelistStatus(msg_.optionsData.target);\\n        _checkWhitelistStatus(OFTMsgCodec.bytes32ToAddress(msg_.lzSendParams.sendParam.to)); // <---- This validation is wrong \\n        // rest of code\\n        \\n        \\n   }\\n```\\n\\n`msg_.lzSendParams.sendParam.to` corresponds to the address that will obtain the tokens in the destination chain after bridging the exercised option, which can and should actually be any address that the user exercising the option decides, so this address shouldn't be required to be whitelisted in the protocol's Cluster (given that the Cluster only whitelists certain protocol-related addresses such as contracts or special addresses).\\nBecause of this, transactions where users try to bridge the exercised options will always fail because the `msg_.lzSendParams.sendParam.to` address specified by users will never be whitelisted in the Cluster.

Impact:
High. The functionality of exercising options and bridging them in the same transaction is one of the wide range of core functionalities that should be completely functional in Tapioca. However, this functionality will always fail due to the mentioned issue, forcing users to only be able to exercise options in the same chain.

Recommended mitigation:
Remove the whitelist check against the `msg_.lzSendParams.sendParam.to` param inexerciseOptionsReceiver():\\n```\\n// UsdoOptionReceiverModule.sol\\n\\nfunction exerciseOptionsReceiver(address srcChainSender, bytes memory _data) public payable {\\n        // Decode received message.\\n        ExerciseOptionsMsg memory msg_ = UsdoMsgCodec.decodeExerciseOptionsMsg(_data);\\n  \\n        _checkWhitelistStatus(msg_.optionsData.target);\\n// Remove the line below\\n        _checkWhitelistStatus(OFTMsgCodec.bytes32ToAddress(msg_.lzSendParams.sendParam.to)); \\n        // rest of code\\n        \\n        \\n   }\\n```\\n