Feat/poseidon2

[ThomasPiellard]

Description

Implementation of poseidon2 for t=2,3 following reference implementation reference paper TBD: algos 1, 2, 3 of https://tosc.iacr.org/index.php/ToSC/article/view/8913/8489 for finding internal matrices when t>3

see gnark-crypto's corresponding PR

Type of change

• [ ] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] This change requires a documentation update

How has this been tested?

see TestPoseidon2, tested against gnark-crypto's implementation

How has this been benchmarked?

scs: 632 constraints for t=3 r1cs: 243 constraints for t=3

Checklist:

• [x] I have performed a self-review of my code
• [x] I have commented my code, particularly in hard-to-understand areas
• [x] I have made corresponding changes to the documentation
• [x] I have added tests that prove my fix is effective or that my feature works
• [x] I did not modify files generated from templates
• [x] golangci-lint does not output errors locally
• [x] New and existing unit tests pass locally with my changes
• [x] Any dependent changes have been merged and published in downstream modules