Verify "list interfaces" Nova v2/v3 API response attributes

This patch adds checks whether a response of
Nova list interfaces v2/v3 API includes the attributes
to block the backward incompatibility change in the future.

The response body of v2 API is the following:
{
    "interfaceAttachments": [
        {
            "port_state": "ACTIVE",
            "fixed_ips": [
                {
                    "subnet_id": "66175fc3-1f21-49c9-84e5-f0eca1831b20",
                    "ip_address": "10.0.0.2"
                }
            ],
            "port_id": "d7a42d37-78ec-4f18-8a9c-1b37c206a733",
            "net_id": "18095bfd-0ab8-4207-99bd-dbdc373bd670",
            "mac_addr": "fa:16:3e:fc:65:ac"
        }
    ]
}

The response body of v3 API is the following:
{
    "interface_attachments": [
        {
            "port_state": "ACTIVE",
            "fixed_ips": [
                {
                    "subnet_id": "66175fc3-1f21-49c9-84e5-f0eca1831b20",
                    "ip_address": "10.0.0.2"
                }
            ],
            "port_id": "d7a42d37-78ec-4f18-8a9c-1b37c206a733",
            "net_id": "18095bfd-0ab8-4207-99bd-dbdc373bd670",
            "mac_addr": "fa:16:3e:fc:65:ac"
        }
    ]
}

Partially implements blueprint nova-api-attribute-test

Change-Id: I44d6ed17db563143be57564780beea8343bd170e
Merge "Verify "list interfaces" Nova v2/v3 API response attributes"