feat!: make schnorr use poseidon

[kashbrti]

Description

This PR changes Schnorr library to use Poseidon hash instead of pederson + blake.
This is a breaking change and any code using this library has to be updated.

Problem*

Resolves

Summary*

Additional Context

I'm unsure about whether we would need to range constraint the sig_e in assert_valid_signature. I have convinced myself that this can not be an issue, since calculate_signature_challenges calculates e with a poseidon hash and if the sig_e byte value is wrapping, it wouldn't match.
More concretely the sig_e and e should match both modulo BN254_Fq and BN254_Fr (one in the msm the other in the validity check).

PR Checklist*

• I have tested the changes locally.
• I have formatted the changes with Prettier and/or cargo fmt on default settings.

[kashbrti]

@TomAFrench I added an explanation in the context so you could double-check.

[ledwards2225]

@kashbrti and I discussed the issue about range constraints and concluded that things are fine as-is. sig_e is range constrained to be < BN254 Fr modulus as an integer by virtue of passing through cycle_group::batch_mul via multi_scalar_mul