Add multus annotation support to the operator

Multus enables users to specify an IP address of the pod on creation, this is an example:

  annotations: 
    k8s.v1.cni.cncf.io/networks: '[
            { 
              "name": "vlan-20",
              "ips": [ "192.168.20.88/24" ],
              "default-route": ["192.168.20.1"]
            }
    ]'

Currently, the client is updating their deployment manually but the operator rewrites the deployment on each reconciliation so these changes are lost. They would like a way to add this annotation to the operator.

Thanks!