Add autolink (linkify) functionality to Markdown

[morrisseyai]

PR updates the commonmark-java dependency to 0.20.0 and introduces autolink (linkify) functionality.

I have added MarkdownParseOptions which allows consumers of the library to control whether or not the autolink functionality is enabled. Addresses #95

Note: autolink is enabled with the new MarkdownParseOptions defaults, which means there is a minor (but worth mentioning) behaviour change here.

Short demo:

https://user-images.githubusercontent.com/8967185/197316145-59e72a17-5bf2-4e8f-b191-eccef2401064.mp4

[halilozercan]

Thanks 🎉