[Libvirt-cim] [PATCH 0 of 3] Add support for setting nic target device

Per the libvirt documentation, users can specify a network interface's target device. If one isn't provided, libvirt will set one automatically. So this is optional setting. Also per the documentation, a target device name cannot start with 'vnet' or 'vif'. These values are reserved. A corresponding test case is also being submitted.