message: core: add missing dtors
diff: @@ -73,6 +73,8 @@ private:
  _progress_callback(std::move(progress_callback))
  {}
  + virtual ~DownloadItem() = default;
  +
  [[nodiscard]] std::string get_local_path() const { return _local_path; }
  [[nodiscard]] std::string get_url() const { return _url; }
  @@ -100,6 +102,8 @@ private:
  _progress_callback(std::move(progress_callback))
  {}
  + virtual ~UploadItem() = default;
  +
  [[nodiscard]] std::string get_local_path() const { return _local_path; }
  [[nodiscard]] std::string get_target_url() const { return _target_url; }
  