libvirt_vm: Add method to create install cmd with sec_label

Signed-off-by: Dongsheng Yang <yangds.fnst@cn.fujitsu.com>
Add test for svirt in virt-install.

Signed-off-by: yangdongsheng <yangds.fnst@cn.fujitsu.com>
guest-os: Add filter for svirt_install in guest-os.

Signed-off-by: Dongsheng Yang <yangds.fnst@cn.fujitsu.com>