Load Balancer - Filter load balancer by front end public ip

Filter to select load balancers with an ipv6 frontend public IP.

policies:
   - name: loadbalancer-with-ipv6-frontend
     resource: azure.loadbalancer
     filters:
        - type: frontend-public-ip
          key: properties.publicIPAddressVersion
          op: in
          value_type: normalize
          value: "ipv6"