add a loading bar (#159)

- when loading icons
- when downloading via QR
- when loading list in the browser
- when loading preview/BGM in the browser
- when downloading from the browser

include/draw.h

@@ -93,6 +93,7 @@ bool draw_confirm(const char* conf_msg, Entry_List_s* list);
 void draw_preview(ssize_t previewID, int preview_offset);
 
 void draw_install(InstallType type);
+void draw_loading_bar(u32 current, u32 max, InstallType type);
 
 void draw_base_interface(void);
 void draw_grid_interface(Entry_List_s* list, Instructions_s instructions);