Function mm0b_parser::find_header_error

#[must_use]
pub fn find_header_error(mmb: &[u8]) -> ParseError

In the event that MmbFile::parse fails when parsing the header, use this to get a more detailed error report (since the zerocopy parser for Header is just pass/fail). This method will panic if it’s not able to find a problem with the header, since a disagreement with MmbFile::parse means something else is going on that needs to looked at.