feat: commit-reveal module

[seanmc9]

have draft in #1529

• module has commit and reveal periods, both within the voting period of the underlying contest
• commit-reveal contests must have a 0 voting merkle root - we verify that it's the official commit-reveal module doing the voting in the vote transaction
• at reveal, they sign in w Ethereum, we give them the info, and they send in this info and we also check on smart contract level that the voter is the one revealing so they ultimately decide if their committed votes get counted.
• one commit with all of your votes - for UX so users only have to sign one message to reveal, but also has added benefit of making it super straightforwards to update a commit if needed, whereas multiple commits (like a commit per proposal voted on would not really be updatable)
  • so the data structure that will get committed is keccack(VoteData[], salt) where VoteData is uint256 proposalId, uint8 support, uint256 numVotes (from castVoteWithoutProof())