Migrate MathJax/Node-based LaTeX renderer to a native library

[fwcd]

This might be a good way to slim down the image too, given that the Node folder takes around 80 MB. Libraries worth investigating:

• MicroTeX: Might be worth considering, especially as Swift-C++ interop is getting better
• SwiftMath, as a port of iosMath: Currently only for Apple platforms due to dependencies on Core Text, Core Graphics etc., but could perhaps be ported?