ZTS: Add zfs/zpool JSON sanity tests
Run basic JSON validation tests on the new zfs|zpool -j output.
Reviewed-by: Ameer Hamza <ahamza@ixsystems.com>
Reviewed-by: Umer Saleem <usaleem@ixsystems.com>
Signed-off-by: Tony Hutter <hutter2@llnl.gov>
Closes #16217