Import window as a widget

The following image is an actual screenshot of the Kdenlive's import pop-up window on Plasma-desktop.

If this can be managed to work as a widget, it could be embedded as a Media Library in the 1st layout 'logging' to preview and import clip by dragging and dropping in the project bin.

"Ok" and "Cancel" buttons should be removed and instead of the file name input box some basic info about the selected file/folder could be shown for convenience.

The import pop-up window should be preserved to allow users fast import when they are in more advanced work stage and to not change the way several people are in habit of.