mosquitto, influxdb: the provisioner sees its grants where the mesh writes them

The received grants file names each pair secret by its HOST path. A sidecar
that mounts the placed grants directory at another path inside its
container sees mesh.json and not the secrets beside it — mosquitto's
provisioner reported ENOENT for a file that was there, and nodered's mqtt
step failed against a login that was never created. Mounted at its own
path now, as postgres does.

modules/mosquitto/module.json

@@ -131,12 +131,12 @@
       "network": "mosquitto",
       "volumes": [
         "/var/lib/mesh/mosquitto/broker:/run/secrets/broker:ro",
-        "${dir:grants}:/var/lib/mosquitto-module/grants:ro",
+        "${dir:grants}:${dir:grants}:ro",
         "/var/lib/mesh/mosquitto/admin:/run/secrets/admin:ro"
       ],
       "env": {
         "MESH_BROKER_FILE": "/run/secrets/broker",
-        "MESH_RECEIVES": "/var/lib/mosquitto-module/grants/mesh.json",
+        "MESH_RECEIVES": "${dir:grants}/mesh.json",
         "MESH_PROVISION_MQTT": "mosquitto:1883",
         "MESH_PROVISION_ADMIN_USER": "mesh-admin",
         "MESH_PROVISION_PASSWORD_FILE": "/run/secrets/admin"