refactor: move poseidon2 to permutation package

[ivokub]

Description

We have two package std/hash and std/permutation, imo for Poseidon2 as it implements only the permutation without full hash it makes sense to move it to std/permutation package.

It is a breaking change but I guess it is fine as the package is very new.

Type of change

• Breaking change (fix or feature that would cause existing functionality to not work as expected)

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