zloop: introduce the zone_append configuration parameter

zloop: introduce the zone_append configuration parameter

A zloop zoned block device declares to the block layer that it supports
zone append operations. That is, a zloop device ressembles an NVMe ZNS
devices supporting zone append.

This native support is fine but it does not allow exercising the block
layer zone write plugging emulation of zone append, as is done with SCSI
or ATA SMR HDDs.

Introduce the zone_append configuration parameter to allow creating a
zloop device without native support for zone append, thus relying on the
block layer zone append emulation. If not specified, zone append support
is enabled by default. Otherwise, a value of 0 disables native zone
append and a value of 1 enables it.

Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>