t/zbd: Add -o option to t/zbd/test-zoned-support

t/zbd: Add -o option to t/zbd/test-zoned-support

To specify maximum open zones of the test target device, add -o option
to t/zbd/test-zoned-support. When this option is specified, add
max_open_zones option to all fio commands in the test script. The option
ensures the number of zones opened by fio is within the limit. This is
useful when the test target device has maximum open zones limit.

When the fio command does not have multiple jobs and the test case does
not specify max_open_zones, add single max_open_zones option to the fio
command line.

When the fio command takes multiple jobs, add max_open_zones option to
each job. Introduce job_var_opts variable to keep options to be added to
each job. To distinguish it from global options for all jobs, rename
var_opts variable to global_var_opts. When a test case with multiple jobs
always specifies max_open_zones option, exclude the max_open_zones option
from job_var_opts, using job_var_opts_exclude() helper function.

Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Reviewed-by: Dmitry Fomichev <dmitry.fomichev@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>