This patch allow kube-ovn-controller combine multus-cni to allocate addresses for subnet providers other than ovn by annotate pods with allocated addresses. Users need to create subnet CRs and set the provider with <name>.<namespace> of NetworkAttachmentDefinition defined by multus-cni. Then kube-ovn-controller will combine the `k8s.v1.cni.cncf.io/networks` annotation and address information in subnet cr to determine an address.

This patch only implement the controller side logical, we need other patches to complete the cni part that communicates to apiserver and fetch the address information to the main cni.