feat: baby-bear and koala-bear extensions of degree 4

[yelhousni]

Description

This PR implements the arithmetic of finite field extensions of degree 4 over koala-bear and baby-bear fields. The implementation is a quadratic-over-quadratic tower using Karatsuba routines. The parameters are:

baby-bear:
𝔽r²[u] = 𝔽r/u²-11
𝔽r⁴[v] = 𝔽r²/v²-u

koala-bear:
𝔽r²[u] = 𝔽r/u²-3
𝔽r⁴[v] = 𝔽r²/v²-u

TODO:

• asm 𝔽r² arithmetic
• implement direct 𝔽r⁴ extension (should be useful soon for cross-checking with gnark implementation)
• generify code

Type of change

• New feature (non-breaking change which adds functionality)

How has this been tested?

All relevant tests implemented.

How has this been benchmarked?

TODO

Checklist:

• I have performed a self-review of my 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 did not modify files generated from templates
• golangci-lint does not output errors locally
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules

[gbotrel]

if we remove the MulBy11 the PR will be cleaner.

Plus of course, need to generify that :)