Add Safe-Extension option to Latex (MathJax)

This a follow-up from !72733 (comment 710324672)

MathJax seems to be super flexible in what they allow, for example https://docs.mathjax.org/en/latest/input/tex/extensions/textmacros.html. And the Google blog post is super interesting in that regards.

Something interesting is https://docs.mathjax.org/en/latest/options/safe.html which has a bunch of options like blocking javascript.

Proposal

We should implement https://docs.mathjax.org/en/latest/options/safe.html to improve security for MathJax usage.