I added the following usefull functions in `GDriveUrl`:
- `QString filename() const`
- `bool isRoot() const`
- `bool isAccountRoot() const`
- `bool isTrashDir() const`
- `bool inTrash() const`
- `QUrl url() const`
- `QString parentPath() const`
- `GDriveUrl parent() const`
and also made use of them in `KIOGDrive`. This improves readability there as it mostly removes all logic based on path components.