qga-win: fix "guest-get-fsinfo" wrong filesystem type

qga-win: fix "guest-get-fsinfo" wrong filesystem type

This patch handles the case where unmounted volumes exist,
where in that case GetVolumePathNamesForVolumeName returns
empty path, GetVolumeInformation will use the current working
directory instead.
This patch fixes the issue by opening a handle to the volumes,
and using GetVolumeInformationByHandleW instead.

Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=1746667
Signed-off-by: Basil Salman <bsalman@redhat.com>
Signed-off-by: Basil Salman <basil@daynix.com>
*fix crash when guest_build_fsinfo() sets errp multiple times
*make new error message more distinct from existing ones
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>