null_blk: Introduce the zone_full parameter

Allow creating a zoned null_blk device with the initial state of its
sequential write required zones to be FULL. This is convenient to avoid
having to first write these zones to perform read performance evaluation
or test zone management operations such as zone reset (and zone reset
all).

Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20240704052816.623865-2-dlemoal@kernel.org


Signed-off-by: Jens Axboe <axboe@kernel.dk>