Cleanup std::hash

[olehmisar]

The list is not exhaustive

• [ ] Rename sha256_var(msg: [u8; N], message_size: u64) -> sha256(input: BoundedVec<u8, N>)
• [ ] Rename keccak256(input: [u8; N], message_size: u32) -> keccak256(input: BoundedVec<u8, N>)
• [ ] Add std::hash::poseidon2(input: BoundedVec<Field, N>)
• [ ] Remove std::hash::poseidon2::Poseidon2::hash
• [ ] Rename poseidon2_permutation(_input: [Field; N], _state_length: u32) -> poseidon2_permutation(_input: BoundedVec<Field, N>)
• [ ] Remove fn sha256 and fn digest from std::hash::sha256
• [ ] Remove std::sha256 and std::sha512 modules
• [ ] IDK what has to be done to cleanup std::hash::poseidon
• [ ] Move tests into mod tests { }

I am not sure about this:

• [ ] Rename std::hash::pedersen_hash -> std::hash::pedersen? Can it accept a BoundedVec?
• [ ] What's up with std::hash::hash_to_field? Should it go to v1?

[olehmisar]

my_hash(input: BoundedVec<u8, N>) may also be written as my_hash(input: impl Into<BoundedVec<u8, N>>), so it can accept both [u8; N] and BoundedVec<u8, N>.

[Savio-Sou]

Hey @olehmisar thanks for submitting the Issue, this is a great collection of suggestions!

The team is currently occupied with gradually moving most of the hashing schemes currently in stdlib out to standalone repos (e.g. MiMC) as a part of https://github.com/noir-lang/noir/issues/6676.

They would be more able to chime in and share thoughts then 🙌 great to continue keep track of observations here for now!