feat(bls12-381): pairing using direct Fp12 + non-native Eval()

[yelhousni]

Description

Similar to #1312 and #1339 but for BLS12-381.

Type of change

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

How has this been tested?

• New tests corresponding to new methods.
• PairingCheck and FinalExpCheck tests against gnark-crypto.

How has this been benchmarked?

size-2 pairing check circuit, i.e. e(a,b)e(c,d)==1, in a BN254-PLONK:

• old: 4,586,709 scs
• new: 2,686,878 scs
  - diff: 1,899,831 scs

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

[ivokub]

Looks perfect! Only a small comment about a duplicate code and potential refactor, but I think we can keep the refactor in a separate PR. And imo it is only small thing, dunno if it is worth it.