[native_pdf_renderer] Include more PDF metadata in PdfDocument

[jbx1]

Is your feature request related to a problem? Please describe. The meta data of the PDF is currently not available in the PdfDocument. This means that to access things like the PDF's title and subject, one has to use another library, bloating up the size of the app. Currently only the number of pages is provided.

Describe the solution you'd like Additional PDF meta data included in the PdfDocument such as document Title, Subject and Author.