Add compatibility for dompdf > 1.2.1.
Implement autoload.inc.php fix for dompdf versions greater than 1.2.1 (including 2.0.0).
Change inspired from https://www.drupal.org/project/print/issues/3031927#comment-14542779
See related security announcement: https://www.drupal.org/sa-contrib-2022-048 https://github.com/dompdf/dompdf/releases/tag/v2.0.0