Auto discovery deactivation at runtime by MQTT command (#856)

and switch automatic creation for it in HASS (by autodiscovery :-)

main/ZgatewayBT.ino

@@ -612,7 +612,8 @@ void coreTask(void* pvParameters) {
         // Launching a connect every BLEscanBeforeConnect
         if (!(scanCount % BLEscanBeforeConnect) || scanCount == 1)
           BLEconnect();
-        launchDiscovery();
+        if (disc)
+          launchDiscovery();
         dumpDevices();
       }
       if (low_power_mode) {