Fix path traversal issue when extracting an .okular file
Summary:
With specially crafted .okular files you can trick okular to create temporary files outside the temporary folder
We fix that by making sure the file doesn't have folders since the ones we create don't
BUGS: 398096
Subscribers: okular-devel
Tags: Okular
Differential Revision: https://phabricator.kde.org/D15192