Report default quotas via kernel interfaces

Ensure default user/group/project quotas are visible through quota
tools and filesystem stats when no per-ID quota is configured. This
maintains consistency between quota visibility and configured defaults.

Signed-off-by: Ameer Hamza <ahamza@ixsystems.com>

Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>