Add a metric that reports the Network Attachment Definitions and their properties.
The goal is to be able to identify what external network each VM is connected to.
We need to check if to add the new metric to openshift/multus-admission-controller or as part of CNV.

Like: network_attachment_definition_info
namespace, network_name, cni_type  (bridge, macvlan, sriov, ovs, etc.), vlan_name,
udn (true / false), ipam (static, dhcp) - report only if it exists in the NAD, multus_enabled (true / false), 
For cni_type="ovn-k8s-cni-overlay"  set "subnets_defined" (true / false), based on whether subnets are defined in the NAD.

Note: This feature require kubevirt VEP and detailed design document.