tg_cli: get business connection when try to send a message to it.

td/telegram/cli.cpp

@@ -1511,6 +1511,7 @@ class CliClient final : public Actor {
         if (!message->is_outgoing_ && use_test_dc_) {
           auto old_business_connection_id = std::move(business_connection_id_);
           business_connection_id_ = update->connection_id_;
+          on_cmd("gbc");
           send_message(message->chat_id_,
                        td_api::make_object<td_api::inputMessageText>(as_formatted_text("Welcome!"),
                                                                      get_link_preview_options(), true),