nodered: the sidecar dials the port it was given

The sidecar runs on the host network and dialled 127.0.0.1:1880, the
software's port; the mesh publishes nodered on a machine port it assigns,
so the tools reached whatever else holds 1880, or nothing (hq 088).

modules/nodered/module.json

@@ -100,7 +100,7 @@
       ],
       "env": {
         "MESH_BROKER_FILE": "/run/secrets/broker",
-        "MESH_NODERED_URL": "http://127.0.0.1:1880",
+        "MESH_NODERED_URL": "http://127.0.0.1:${port:1880}",
         "MESH_NODERED_CONFIG_FILE": "/run/config/config.json"
       },
       "restart-on": [