generic: initial fiemap range query test

generic: initial fiemap range query test

Fiemap gained support for passing in optional offset len which
denote the range requested, so this patch adds testcases for this
functionality. Aditionally, a special "ranged" argument is added to
the require_xfs_io_command which checks for the presence of fiemap
range support.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Eryu Guan <eguan@redhat.com>
Signed-off-by: Eryu Guan <eguan@redhat.com>