Function partial_sha256_var_interstitial

pub fn partial_sha256_var_interstitial<let N: u32>(
    h: [u32; 8],
    msg: [u8; N],
    message_size: u32,
) -> [u32; 8]

Given some state of a partially computed sha256 hash and part of the preimage, continue hashing @notice used for complex/ recursive offloading of post-partial hashing

@param N - the maximum length of the message to hash @param h - the intermediate hash state @param msg - the preimage to hash @param message_size - the actual length of the preimage to hash @return the intermediate hash state after compressing in msg to h