Add a split horizon resolv.conf

- in default namespace, point to 194.1.163.3 and .4
- in dataplane namespace, point to lab.ipng.ch (192.168.1X.4 and 2001:678:d78:2X1::ffff)
- renumber ipv4 transit nets, so that .4/31 is labX.lab.ipng.ch <-> e0.vppX-0
- refactor common args (like nameserver search paths, node count, etc)

Regenerate the whole thing.

overlays/bird/common/etc/netplan/01-netcfg.yaml.j2

@@ -9,6 +9,4 @@ network:
       addresses: [ {{node.mgmt.ipv4}}, {{node.mgmt.ipv6}} ]
       gateway4: {{lab.mgmt.gw4}}
       gateway6: {{lab.mgmt.gw6}}
-      nameservers:
-        addresses: [ "2001:678:d78::3", "2001:678:d78::4" ]
-        search: [ "lab.ipng.ch", "ipng.ch", "ipng.nl", "rfc1918.ipng.nl" ]
+