Support sending is_eof for online websocket server. (#2204)

is_final=true means an endpoint is detected.

is_eof=true means all received samples have been processed
by the server.

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

@@ -210,6 +210,7 @@ void OnlineWebsocketDecoder::Decode() {
 
     if (!recognizer_->IsReady(c->s.get()) && c->eof) {
       result.is_final = true;
+      result.is_eof = true;
     }
 
     asio::post(server_->GetConnectionContext(),