AUTHORS: update with missing names

This is generated by scripts/update_authors.pl. I've looked over the
results fairly closely and while I don't think they're bad, they could
be improved somewhat, but also, I don't know if its good form to just
update this without explicit consent from those named.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Tino Reichardt <milky-zfs@mcmilk.de>
Signed-off-by: Rob Norris <robn@despairlabs.com>
Closes #15374