[kfilewidget] Clear urls before rebuilding the list
When using a QML FileDialog with multiselection the list of selected urls isn't cleared when re-opening the dialog. This is because we keep adding to d->urlList but never clear it.
When using a QML FileDialog with multiselection the list of selected urls isn't cleared when re-opening the dialog. This is because we keep adding to d->urlList but never clear it.