fixing 32bit truncation for HKDF and sp800

[Khang (nnmkhang)]

Description of Changes:

Changed sp800 and hdkf API to output usize rather than u64 to not truncate on 32 bit system

Breaking Changes if any:

HKDF API signature changed:

pub fn hkdf(
    hmac_algorithm: HmacAlgorithm,
    key_material: &[u8],
    salt: &[u8],
    info: &[u8],
    output_key_size: usize, <----- Changed from u64
) -> Result<Vec<u8>, SymCryptError> {

Same applies for Sp800 but the change is not in cargo yet.

✅ Admin Checklist

• Review the PR description and ensure all necessary details are included.
• Update/add unit tests for changed code.
• Update/add documentation for new or changed APIs.
• Run cargo test --all-features on Windows and WSL.

Check the Developer Guidelines in DEVELOPER.md for more info.

[Mitch Lindgren (mlindgren)]

lgtm