The patch tests zone append writes by reporting the zone wp after
the completion of the call. "zap -p" option can print the sector
offset value after completion, which should be the start sector
where the append write begins.

Signed-off-by: Sam Li <faithilikerun@gmail.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 20230508051510.177850-4-faithilikerun@gmail.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>