Support code embedding

[JeroenDeDauw]

AC

• Does not get rendered as markdown :)
• Syntax highlighting. Language auto-detection optional
• Fully tested with automated tests. Unit and integration tests where appropriate

[JeroenDeDauw]

The plugin system for different renders is already in place

[malberts]

Syntax highlighting can possibly be done client side using something like:

• https://highlightjs.org/
• https://prismjs.com/

That way we can avoid the SyntaxHighlight extension which depends on a Python library and which normally expects to be used with the code in the wikitext.

[JeroenDeDauw]

Here is a diagram I created before writing the extension. It's likely somewhat out of date but still conveys the high-level structure:

For this task you presumably need a new ContentRenderer implementation