Correct our arbitrage loop

[0xJepsen]

Right now our arbitrage loop is somewhat of a approximation.
Currently we find the amount in that would push the dex price to the lex price. This is not optimal in the case where we have fees. We would like to account a correct amount in that is correct with fee's. This should make it so that we have a trade that goes through on every update (given we are in the arb bounds)