Optionally use Jsoup for HTML parsing in OpenPDF-html

[andreasrosdal]

Optionally enable using Jsoup for HTML parsing in OpenPDF-html.

https://jsoup.org/
https://github.com/jhy/jsoup/
https://github.com/LibrePDF/OpenPDF/tree/master/openpdf-html

See #1419 where the current html parser doesn't work on Android.

So in addition to the current htmlunit-neko html parser, allow using Jsoup.
https://github.com/HtmlUnit/htmlunit-neko