zdb: bring crash handling over from ztest

ztest has a very nice ability to show a backtrace when there's an
unexpected crash. zdb is used often enough on corrupted data and can
blow up too, so nice output is useful there too.

Sponsored-by: Klara, Inc.
Sponsored-by: Wasabi Technology, Inc.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Rob Norris <rob.norris@klarasystems.com>
Closes #16181