IP fields on virtual circuit network-services-configs

GET network-services:

1. subnet_v4, subnet_v6 fields are only available for type exchange_lan

GET network-services-configs:

1. ips/asns fields are only available for type exchange_lan

We have a special type of mp2mp_vc which does have IP ranges assigned to it. IX-API currently does not provide a way to expose the IPs allocated to virtual circuit network-service-configs, nor the subnet information on the network-service itself.