Allow rendering typst/latex formulas

[mfontanini]

This adds support for rendering typst/latex formulas by tagging code blocks with the right language (typst and latex respectively) and using the +render property on them. For this to work you need:

• Typst. This is the rendering engine used for both formats.
• If you want latex fomulas, you need typst and pandoc. This is used to transform latex into typst before rendering it.

The rationale behind using typst for this is that the language requires no bloat to do this as opposed to latex, and it produces pngs directly rather than going through an intermediate pdf step which simplifies things greatly.

PS: I still need to test this a bit more but this in a working state.