Harden receiver ingest against unknown senders

src/data_model.cpp

@@ -21,6 +21,8 @@ const char *rx_reject_reason_text(RxRejectReason reason) {
       return "device_id_mismatch";
     case RxRejectReason::BatchIdMismatch:
       return "batch_id_mismatch";
+    case RxRejectReason::UnknownSender:
+      return "unknown_sender";
     default:
       return "none";
   }