fn prepend_header(compressed_state_diffs: Vec<u8>) -> Vec<u8> {
    let mut res = vec![0u8; 5];
    res[0] = COMPRESSION_VERSION_NUMBER;

    res[1..4].copy_from_slice(&(compressed_state_diffs.len() as u32).to_be_bytes()[1..4]);

    res[4] = BYTES_PER_ENUMERATION_INDEX;

    res.extend(compressed_state_diffs);

    res.to_vec()
}
Adds the header to the beginning of the compressed state diffs so it can be used as part of the overall
pubdata. Need to prepend: compression version || number of compressed state diffs || number of bytes used for
enumeration index.
core/lib/types/src/storage/writes/mod.rs