Implement Miller-Rabin primality testing for prime-related functions

[Mego]

Ideally, this will be a standalone implementation - no reliance on numpy or sympy. I'd like to avoid adding those as requirements, as they're quite large libraries.

The implementation must be deterministic.

Bonus points for using the current-best set of witnesses to ensure accuracy for very large numbers.

[misingnoglic]

On it :)

[Mego]

Next step: using MR for primality testing for the prime-related commands. I'll work on this :)

[Mego]

@misingnoglic As I mentioned on the PR that I prematurely merged, the implementation you wrote does not meet the requirements, because it is not a deterministic implementation.