Fix incorrect type conversion in case of libraries lookup name collision

[montyly]

Slither was incorrectly converted some of the types in case of implicit conversion on library lookup

Ex:

library Lib{
    function t(uint, uint8) internal returns(uint){
        return 0x1;
    }
    function t(uint, uint256) internal returns(uint){
        return 0x32;
    }

}


contract Test{
    function test() public view returns(uint){
        uint a;
        return a.t(0x10);
    }
}

The IR would incorrectly uses t(uint, uint256).