Add the zonemode job option

Add the zonemode job option

Fio's zone support makes fio perform I/O inside a zone before it skips
to the next zone. That behavior is the opposite of the behavior needed
for zoned block devices, namely to consider all zones when performing
random I/O. Hence introduce a new job option that allows users to
choose between fio's traditional zone mode and the behavior needed for
zoned block devices. This patch makes fio behave identically with
--zonemode=none and --zonemode=zbd. A later patch will implement new
behavior for --zonemode=zbd.

Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>