nixos/scion: changes for 0.12

These are the necessary changes for updating to 0.12, which supports dispatcherless operation by foregoing the dispatcher's unix socket in favour of UDP

nixos/modules/services/networking/scion/scion-control.nix

···
     general = {
       id = "cs";
       config_dir = "/etc/scion";
-      reconnect_to_dispatcher = true;
     };
     beacon_db = {
       connection = "${connectionDir}/scion-control/control.beacon.db";

nixos/modules/services/networking/scion/scion-daemon.nix

···
     general = {
       id = "sd";
       config_dir = "/etc/scion";
-      reconnect_to_dispatcher = true;
     };
     path_db = {
       connection = "${connectionDir}/scion-daemon/sd.path.db";

nixos/modules/services/networking/scion/scion-dispatcher.nix

···
   defaultConfig = {
     dispatcher = {
       id = "dispatcher";
-      socket_file_mode = "0770";
-      application_socket = "/dev/shm/dispatcher/default.sock";
+      local_udp_forwarding = true;
     };
     log.console = {
       level = "info";

nixos/tests/scion/freestanding-deployment/topology1.json

···
 {
+  "dispatched_ports": "31000-32767",
   "attributes": [
     "core"
   ],

nixos/tests/scion/freestanding-deployment/topology2.json

···
 {
+  "dispatched_ports": "31000-32767",
   "attributes": [
     "core"
   ],

nixos/tests/scion/freestanding-deployment/topology3.json

···
 {
+  "dispatched_ports": "31000-32767",
   "attributes": [
     "core"
   ],

nixos/tests/scion/freestanding-deployment/topology4.json

···
 {
+  "dispatched_ports": "31000-32767",
   "attributes": [],
   "isd_as": "42-ffaa:1:4",
   "mtu": 1472,

nixos/tests/scion/freestanding-deployment/topology5.json

···
 {
+  "dispatched_ports": "31000-32767",
   "attributes": [],
   "isd_as": "42-ffaa:1:5",
   "mtu": 1472,