support configurable topic root https://github.com/meshtastic/firmware/issues/2380

meshtastic/module_config.options

@@ -3,6 +3,7 @@
 *MQTTConfig.address max_size:64
 *MQTTConfig.username max_size:64
 *MQTTConfig.password max_size:64
+*MQTTConfig.root max_size:16
 
 *AudioConfig.ptt_pin int_size:8
 *AudioConfig.i2s_ws int_size:8

meshtastic/module_config.proto

@@ -61,6 +61,12 @@ message ModuleConfig {
      * If true, we attempt to establish a secure connection using TLS
      */
     bool tls_enabled = 7;
+
+    /*
+     * The root topic to use for MQTT messages. Default is "msh".
+     * This is useful if you want to use a single MQTT server for multiple meshtastic networks and separate them via ACLs
+     */
+    string root = 8;
   }
 
   /*