Bridge and SRIOV VF Network Interface VLAN Tag Selection Support

[BlaringIce]

Per the libvirt XML format documentation, when using an interface type of 'bridge' with OVS, 'hostdev', 'direct', and 'passthrough', trunked traffic can be specified on a per-interface basis to amp specific VLAN id tags' traffic. It would be nice, when detected to be using one of these interface types, to be able to select these tags through the cockpit-machines GUI instead of being required to fall back to virsh to manage that aspect of VMs.

[BlaringIce]

Referenced libvirt documentation: https://libvirt.org/formatdomain.html#id62