Implement U256InvModN hint

[Sh0g0-1758]

Fixes: #630

[Sh0g0-1758]

I found the rust implementation to be over engineered, so I followed the python implementation which was very straightforward and is passing the tests. I think performance of both should be the same. But happy to hear your thoughts on it. The tests are done on the examples given here

[cicr99]

Looks very good. I thought you could use the uint256 library for this instead of bigInt, but it's better this way, all the methods are already using bigInt anyway