title: Have a puppeteer generated PDF pass accessibility reports
body: <p>I'm building PDFs using Puppeteer, the resulting PDF looks nice but it is failing PDF Accessibility reports.
  The main issues have been the title of the PDF, and the Language of the PDF.
  I have tried setting both via EXIF values (<code>Title</code>, <code>Language</code>), the title does display in certain cases but still fails Acrobat Pro's accessibility check report.
  I have used another accessibility check report ( <a href="http://checkers.eiii.eu/en/pdfcheck/" rel="nofollow noreferrer">http://checkers.eiii.eu/en/pdfcheck/</a> ) and there the title is set successfully but not the language.</p>
  <p>I have used <code>--export-tagged-pdf</code> as a launch parameter which fixed many other issues.</p>
  <p>Would anyone have an idea how I could pass the accessibility report please? Mostly the language parameter. I'm using Node.js to generate the PDFs, even if there is another library to edit the PDF after the fact that would be really helpful, I wasn't able to figure that out.</p>