add upload progress bar

src/components/progressbar.hpp

@@ -0,0 +1,11 @@
+#pragma once
+#include <gtkmm/progressbar.h>
+#include <string>
+
+class MessageUploadProgressBar : public Gtk::ProgressBar {
+public:
+    MessageUploadProgressBar();
+
+private:
+    std::string m_last_nonce;
+};