Round-trip reinterpret of all isbits types (#47116)
Hiding padding bytes in the process, to avoid undefined behavior if
those are observed.
Co-authored-by: Andy Ferris <andy.ferris@roames.com.au>
Co-authored-by: Jameson Nash <vtjnash@gmail.com>
Co-authored-by: Sukera <11753998+Seelengrab@users.noreply.github.com>
