Attempt to disable LaTeX rendering on the front-end when we observe that
the given assistant has the LaTeX rendering option disabled.

Previously, the assistant's LaTeX rendering option only determined
whether we would inject additional instructions on the backend to try to
elicit better quality LaTeX from the LLM.

Fix is to add more runtime rendering options to the Markdown rendering
component. Currently we only support syntax highlighting and LaTeX
extensions, but in the future we can add more rendering extensions and
condition them on rendering context with this same method.

Fixes #406