add get_all_channel_request

admin.proto

@@ -175,6 +175,11 @@ message AdminMessage {
      */
     bool confirm_set_module_config = 17;
 
+    /*
+     * Send all channels in the response to this message
+     */
+    bool get_all_channel_request = 18;
+
     /*
      * Setting channels/radio config remotely carries the risk that you might send an invalid config and the radio never talks to your mesh again.
      * Therefore if setting either of these properties remotely, you must send a confirm_xxx message within 10 minutes.