Markdown: Add support for rendering latex in markdown preview (and in chat panel)

[isaacveg]

In VSCode, the math rendering is effective across markdown files, doc strings of functions, and chat with AI. As someone who's doing machine learning research, asking AI to explain something with clear math is a must for me. Current Zed does not support math rendering across the app, which makes reading AI responses or writing markdown notes painful.

A workaround would be copying the response into markdown and pasting it into some markdown reader, ironically, VSCode. But a straight support for directly rendering LaTeX would be so wonderful.

I checked a previous issue (#40813), and this might be helpful:
https://github.com/KenyC/ReX

I understand implementing such things in GPUI from scratch is not easy, and I'm not pushing anyone to do this, but to know whether it would take a long time.