Allow to drop one file or one folder on KDirOperator
Summary:
BUG: 45154
FIXED-IN: 5.59
Test Plan:
- Manual testing using kfilewidgettestgui.cpp and kfilewidgettest_saving_gui.cpp
- added automated test
Reviewers: ngraham, Frameworks
Reviewed By: ngraham
Subscribers: elvisangelaccio, apol, kde-frameworks-devel
Tags: Frameworks
Maniphest Tasks: T8552
Differential Revision: https://phabricator.kde.org/D20838