feat: add BN254 final exponentiation check with output

[ivokub]

Description

In some cases we are interested to obtain the value if the final exponentiation resulted in 1 or not instead of asserting. Refactor and add such method.

With this, also renamed FinalExpCheck to AssertFinalExpCheck to better distinguish different methods.

Type of change

• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

How has this been tested?

• TestIsMillerLoopAndFinalExpCircuitTestSolve
• TestMillerLoopAndMulTestSolve

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

[yelhousni]

LGTM! just made same renaming suggestions.

[ivokub]

Applied the review suggestions + added documentation for IsMillerLoopAndFinalExpOne. Will wait for CI before merge.