The browser-based PDF export doesn't pass accessibility checks

Create a simple wiki page with content like this:

= Section One =

Text before.

[[image:attach:Sandbox.WebHome@XWikiLogo.png||alt="XWiki Logo"]]

== Section Two ==

End text.

then export it to PDF using the client-side (browser-based) export. Take the generated PDF and verify its accessibility. I tried with:

• https://checkers.eiii.eu/en/pdfcheck/ which showed 3 issues:
  • language not set (PDF16: Setting the default language using the /Lang entry in the document catalog of a PDF document)
  • title not set (PDF18: Specifying the document title using the Title entry in the document information dictionary of a PDF document)
  • missing bookmarks (PDF2: Creating bookmarks in PDF documents)
• https://pave-pdf.org/pave/ which showed 4 issues:
  • language not set
  • title not set
  • missing alt text on images (PDF1: Applying text alternatives to images with the Alt entry in PDF documents)
  • missing alt text on links (PDF13: Providing replacement text using the /Alt entry for links in PDF documents)