More Mobile app sensor fixes (#22914)

* Ensure we only add a sensor once

* Ensure that we dont process updates for entities that arent what we were setup for

* Add debug logging to ease development of apps

* Use str representation

homeassistant/components/mobile_app/webhook.py

@@ -99,6 +99,9 @@ async def handle_webhook(hass: HomeAssistantType, webhook_id: str,
 
     data = webhook_payload
 
+    _LOGGER.debug("Received webhook payload for type %s: %s", webhook_type,
+                  data)
+
     if webhook_type in WEBHOOK_SCHEMAS:
         try:
             data = WEBHOOK_SCHEMAS[webhook_type](webhook_payload)