NTT Implementation for PolynomialRingZq

[Marvin-Beckmann]

Description

This PR implements the NTT for

• Cyclic Modulus
• Negacyclic Modulus
• multiplication of PolynomialRingZq

Even though I included several optimisations I found, I did not manage to make the implication faster than direct multiplication using FLINT, where the multiplication is already very fast.
I included benchmarks and added an additional disclaimer in the comment of the NTT-multiplication that is is not slower.
I tested it for common parameter-sets that I have found.
I found that the overhead necessary for multithreading also exceeds the runtime of the multiplication, so this was not an option to reduce the runtime, but for future potential optimisations I kept the framework to enable multi-threading within the code-base.

Testing

• I added basic working examples (possibly in doc-comment)
• I triggered all possible errors in my test in every possible way
• I included tests for all reasonable edge cases

Checklist:

• I have performed a self-review of my own code
  • The code provides good readability and maintainability s.t. it fulfills best practices like talking code, modularity, ...
    • The chosen implementation is not more complex than it has to be
  • My code should work as intended and no side effects occur (e.g. memory leaks)
  • The doc comments fit our style guide
  • I have credited related sources if needed

[LPorzenheim]

Tests missing for intt working correctly as well as different modulus (as in ntt)

[LPorzenheim]

Code looks correct when comparing with reference. Minor spelling mistakes and missing tests in intt, see comments.