feat: Groth16 Solidity contract with commitments

[lighterabc]

Description

This PR adds commitment verification to groth16 solidity verifier contract. Contract does not do foldings so uses first commitment for pairing check and uses sha256 hash as hash to field function. I added warning logs about these assumptions

Resolves: #524

Type of change

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

How has this been tested?

• Test case added under internal/backend/circuits/commit.go. Tests depends on changes at feat: add groth16 commitment verifier gnark-solidity-checker#2

How has this been benchmarked?

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 good, thanks!

I'll try to think maybe we can omit the --commitment argument for gnark-solidity-checker. For now it works, but I'm quite certain it would haunt us in the future trying.

And also one part in the Solidity template -- I think it can be simplified a little to be more readable. Otherwise imo looks perfect. I tested locally and works end to end.

[lighterabc]

@ivokub I tried to address some comments you left. Thanks for the review

[ivokub]

I pushed some changes to simplify tests (have options modifying the hash functions for Solidity target automatically). I'll go about running the solidity checks when Consensys/gnark-solidity-checker#2 has been merged and lets see how the tests behave.

[ivokub]

Lets wait for the CI pipeline to finish and I'll also create two new issues for tracking improvement effors, but I think the PR is now good to merge. We really appreciate the contribution and the implementation has been very good! Good work!

[ivokub]

I created new issues for tracking improvements: #1094 and #1095.