virttest.utils_misc: interface to get winutils volume ID

Many test for windows platform need wintuils.iso, but volume ID is
variable, this interface will help to get it from guest os;

Signed-off-by: Xu Tian <xutian@redhat.com>
qemu.tests: modified format_disk tests

Make file content configurable, after this changes this case can be used
as subtest for other tests(eg, iometer_windows, iozone_windows) and no
impact original format_disk tests steps;

Signed-off-by: Xu Tian <xutian@redhat.com>
shared.deps: add icf for for iometer tests

iometer.icf for iometer_windows test, iometer-performance.icf for
iometer-performance test;

Signed-off-by: Xu Tian <xutian@redhat.com>
virt.tests: update iometer_windows tests

use new interface utils_misc.get_winutils_vol() to get winutils cdrom
driver letter; Replace format disk related code with run format_disk sub
tests to avoild duplicate code;

Signed-off-by: Xu Tian <xutian@redhat.com>
virt.tests: update iozone_windows test

use utils_misc.get_winutils_vol() to instead static volume ID, becase
winutils cdrom has different volume ID when use different driver_format
on different windows guest;

Signed-off-by: Xu Tian <xutian@redhat.com>