[BUG] Remove member is problematic on LinkableIncrementalBinaryTree

[semaraugusto]

Describe the bug
By changing from https://github.com/semaphore-protocol/semaphore's default merkleTree to ours LinkableIncrementalBinaryTree.sol we introduced a problem on the removeMember method.

This is caused by our historyRoot array and by the edgeHistory. If a user gets removed from the merkle tree at some block then it could still interact with the contract for at least historySize-1 group modifications. Same stands for edgeHistory, but with the updates being relayer updates for updateEdge.

Possible solutions

1. Set historySize=1.
   This avoids the problem, but introduces a front-running opportunity for denying service to some user.

2. Keep historySize=30, but set currentRootIndex to 0 whenever a removal happens.

This essentially clears the history of merkleRoots, thereby resolving the late interaction problem described above.