Dragging items from basic objects palette causes warnings in the log

BasicObjectsView::startDrag() sets drag pixmap to  index.data(BasicObjectsModel::IconRole).toUrl().toLocalFile(), which is always an empty string, since toLocalFile() can't deal with qrc urls. This causes numerous "QPixmap::scaled: Pixmap is a null pixmap" warnings in the log.

Using QQmlFile::urlToLocalFileOrQrc to get the correct path is probably what should be called instead of toLocalFile. However, it should be checked if setting pixmap here has any visible effect on the drag; perhaps we can just omit this line.