Refs T6421
- "By Folder" navigation works now
- Selection is also possible in "By Folder" view
- On clicking or selecting a folder( which is distinguished by the AlbumDelegate) a new column is pushed to the pageStack
- "By Folder" shows mixed folders and images that are navigable in hierarchy
- SelectedRole from the ImageFolderModel is removed as the ImageFolderModel is wrapped inside that of the SortModel which already implements SelectedRole