Draft: Fancy PDF signatures
I extended Okular's capabilities to digitally sign PDFs with a corresponding signature annotation widget. During the signing workflow, users may provide addtional information as illustrated by this screenshot:
The resulting signatures have:
- calculated font sizes based on the size of the selected signature area
- a background image as selected in the dialog
- additional optional information in the signature based on what users enter into the dialog
This requires changes to poppler, as suggested in https://gitlab.freedesktop.org/poppler/poppler/-/merge_requests/1029