Set is_final and start_time for online websocket server. (#342)

* Set is_final and start_time for online websocket server.

* Convert timestamps to a json array

sherpa-onnx/csrc/online-websocket-server-impl.cc

@@ -195,9 +195,14 @@ void OnlineWebsocketDecoder::Decode() {
   for (auto c : c_vec) {
     auto result = recognizer_->GetResult(c->s.get());
     if (recognizer_->IsEndpoint(c->s.get())) {
+      result.is_final = true;
       recognizer_->Reset(c->s.get());
     }
 
+    if (!recognizer_->IsReady(c->s.get()) && c->eof) {
+      result.is_final = true;
+    }
+
     asio::post(server_->GetConnectionContext(),
                [this, hdl = c->hdl, str = result.AsJsonString()]() {
                  server_->Send(hdl, str);