Support Dualstack IPv6 in AIAP

- Enable infra-build VMs to have valid IPv6 addresses

Closes: #656
DependsOn: I30ef2543d91f574e73a555bf67ab7ec2764a4411
Change-Id: Ibd6ab5c9f7e2ead274d9509c3466484de6918826

tools/airship-in-a-pod/infra-builder/assets/opt/ansible/playbooks/roles/build-infra/defaults/main.yaml

@@ -52,11 +52,17 @@ networks:
     ip:
       address: "10.23.24.1"
       netmask: "255.255.255.0"
+    ipv6:
+      address: "2001:468:181:f200::1"
+      prefix:  "64"
   - name: nat
     bridge: "air_nat"
     ip:
       address: "10.23.25.1"
       netmask: "255.255.255.0"
+    ipv6:
+      address: "2001:468:181:f100::1"
+      prefix:  "64"
   - name: default
     bridge: "default"
     ip:

tools/airship-in-a-pod/infra-builder/assets/opt/ansible/playbooks/roles/build-infra/templates/air_nat.xml.j2

@@ -7,4 +7,6 @@
   </forward><bridge name="nat_br" stp="on" delay="0"/>
   <ip address="{{ networks[1].ip.address }}" netmask="{{ networks[1].ip.netmask }}">
   </ip>
+  <ip family="ipv6" address="{{ networks[1].ipv6.address }}" prefix="{{ networks[1].ipv6.prefix }}">
+  </ip>
 </network>

tools/airship-in-a-pod/infra-builder/assets/opt/ansible/playbooks/roles/build-infra/templates/air_prov.xml.j2

@@ -4,4 +4,6 @@
   <bridge name="prov_br" stp="on" delay="0"/>
   <ip address="{{ networks[0].ip.address }}" netmask="{{ networks[0].ip.netmask }}">
   </ip>
+  <ip family="ipv6" address="{{ networks[0].ipv6.address }}" prefix="{{ networks[0].ipv6.prefix }}">
+  </ip>
 </network>