Add ternary big integers

[thibault-martinez]

Description of change

Add ternary big integers.

Links to any relevant issues

#77

How the change has been tested

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Make sure to provide instructions for the maintainer as well as any relevant configurations.

Change checklist

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• I have followed the contribution guidelines for this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• I have checked that new and existing unit tests pass locally with my changes
• I have updated the CHANGELOG.md, if my changes are significant enough

[samuel-rufi]

It's a quite complex RFC, however from the perspective of the code - besides what Joshua and Alex noticed - it seems ok to me.

[Alex6323]

It is one of the hardest to understand Bee crates so far, and I would need to really deep-dive into the details of it to fully grasp it. I have no doubt, that the code is correctly working as it's cross-checked with other implementations via unit-tests, but the code overall feels a bit over-engineered, and also not very DRY, although I am not sure, the repetitiveness could have been prevented here.