fix(stdlib): Workaround for Field comparison error in EdDSA signature verification

[ax0]

Related issue(s)

Related to #1313

Description

This PR resolves an error that occurs when generating a proof involving EdDSA signature verification: Calling eddsa_poseidon_verify leads to an error on the following example:

use dep::std::eddsa::eddsa_poseidon_verify;

fn main(data: [Field; 6])
{
	assert(eddsa_poseidon_verify(data[0], data[1], data[2], data[3], data[4], data[5]));
}

#[test]
fn test_main()
{
	let data = [0x1f3581c1eb058355ad574689b0bf37ab4e02433492eac1fbcd9fe5ce9272099e,0x0f72436cb679e0fa77342a92342d271bdd869ac14ce1f13a2afcccc5b6f75714,0x03ec6779f0250bb9852b3bc71cfb3dbb21420294fe8ce16ac6469049171b987e, 0x0b317e5deb2cbbc171f7c70ee5f6634563bb3a23f67d001ed9750380bbaf60cf,0x1cad3257ef27851ebd24587ff64230f3be41dfac3e8170878116190527448373,0x1d7ecd14bf6ec1bf60b655ef74e99bc874c76d179b1adc9a81bb55dd4bbacf46];
    

	main(data);
}

nargo test passes, but nargo prove with the following Prover.toml fails with the error not implemented: Field comparison is not implemented yet, try to cast arguments to integer type:

data = ["0x1f3581c1eb058355ad574689b0bf37ab4e02433492eac1fbcd9fe5ce9272099e","0x0f72436cb679e0fa77342a92342d271bdd869ac14ce1f13a2afcccc5b6f75714","0x03ec6779f0250bb9852b3bc71cfb3dbb21420294fe8ce16ac6469049171b987e", "0x0b317e5deb2cbbc171f7c70ee5f6634563bb3a23f67d001ed9750380bbaf60cf","0x1cad3257ef27851ebd24587ff64230f3be41dfac3e8170878116190527448373","0x1d7ecd14bf6ec1bf60b655ef74e99bc874c76d179b1adc9a81bb55dd4bbacf46"]

The problem lies in lt_bytes32, where the compiler is not treating the elements of the byte arrays x_bytes and y_bytes as bytes. This PR adds type casts to force this, which eliminates the above error.

Summary of changes

Added u8 type casts.

Dependency additions / changes

Test additions / changes

Checklist

• I have tested the changes locally.
• I have formatted the changes with Prettier and/or cargo fmt with default settings.
• I have linked this PR to the issue(s) that it resolves.
• I have reviewed the changes on GitHub, line by line.
• I have ensured all changes are covered in the description.

Documentation needs

• This PR requires documentation updates when merged.

Additional context