Extract metadata from PDF

[angelo-v]

As someone who uploaded a PDF file to my Pod, I want the PDF metadata to be extracted and stored to the Pod as RDF as well, so that it becomes part of the Solid ecosystem and can be used with other Apps.

The data should be extractable on upload as well as afterwords, so that I can also get the data from PDFs I uploaded in the past or with apps that don't support this feature