N°2244 - Fix image attributes not being visible in PDF exports

[Molkobain]

Symptom

Image attributes not visible in PDF exports when exporting a list of objects, for example Person and their picture attribute.

Current behavior

Expected

Reproduction

• iTop 2.7.0 + sample data
• Open a list of Person objects
• Export the list in PDF with the picture attribute
• Open the PDF and see the "Picture" column empty

Cause

During the export, images are rendered in HTML as base64-encoded which is fine, but TCPDF requires a special formatting of the src attribute for it to work.

TODOs

• [ ] Add unit test on the PDF size (not great, but difficult to do better)