JSON output support for zfs list

This commit adds support for JSON output for zfs list using '-j' option.
Information is collected in JSON format which is later printed in jSON
format. Existing options for zfs list also work with '-j'. man pages are
updated with relevant information.

Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Ameer Hamza <ahamza@ixsystems.com>
Signed-off-by: Umer Saleem <usaleem@ixsystems.com>
Closes #16217