UI updates

- add import dialog
  this is more complex than I thought
- added scope exit
  grammar sugar
- main dialog is now linked to import dialog
- importer citra file path is fixed
- importer now reports maximum size
- file util is improved with GetDirectoryTreeSize

src/core/importer.h

@@ -33,6 +33,8 @@ struct ContentSpecifier {
     ContentType type;
     u64 id;
     bool already_exists; ///< Tells whether a file already exists in target path.
+    u64 maximum_size; ///< The maximum size of the content. May be slightly bigger than real size.
+    std::string name; ///< Optional. The content's preferred display name.
 };
 
 /**