Optimization tests should support inputs and uint return value

[tuturu-tech]

Currently optimization tests only support optimize_* functions with no inputs and a int output, as visible here. It would be useful to have optimization tests that support inputs and uint outputs as well.

Example of optimization test that currently won't be run:

    function optimize_rateDifference() public returns (uint256) {
        if (newRate < startingRate) {
            return startingRate - newRate;
        }
        return 0;
    }