audit: Multiple Voting if Voting Strategy Calls Untrusted Code

[Orland0x]

There is a possible reentrancy in the vote method of a Space. If the voting strategy calls untrusted code, vote() can be reentered and a user can vote several times, because the voteRegistry is updated only after the interactions (vote counting and incrementing) have happened.

[pscott]

Even though we do trust the voting strategies, it's still better to prevent this bug.

FIX: move voteRegistry[proposalId][voter] = true to before the call to _getCumulativePower