Re-publish BTtoMQTT Theengs discovery topics on MQTT re-connect (#1290)

* Re-publish BTtoMQTT Theengs discovery topics on MQTT re-connect

- Improved version of #1274, this should re-publish more
- Handle return value of (MQTT) client.loop() to detect connection loss
  faster

Signed-off-by: Sami Salonen <ssalonen@gmail.com>

main/config_BT.h

@@ -30,7 +30,7 @@ extern void setupBT();
 extern bool BTtoMQTT();
 extern void MQTTtoBT(char* topicOri, JsonObject& RFdata);
 extern void emptyBTQueue();
-extern void launchBTDiscovery();
+extern void launchBTDiscovery(bool overrideDiscovery);
 
 #ifdef ESP32
 extern int btQueueBlocked;