Have `fmt_markdown()` and `md()` handle LaTeX math formulas

[rich-iannone]

The fmt_markdown(), html(), and md() functions should be able to convert LaTeX math formulas to inline SVGs. This will allow math formulas in table cells and in any other label areas (e.g., column labels, header title, etc.).

The rendered formula SVGs should entirely consist of paths.

[maj-biostat]

Hi @rich-iannone
I have been looking for a way to introduce mathematical notation in the column headers (beyond simple cases such as html("p<sub>y<\sub>") ). Is there a way to do this? I have been scouring the net and documentation for a few hours and cannot seem to find any options. For the current use case, all I want to do is the equivalent of $\hat{p}_y$ but I have other more complex scenarios that I need to use as well. Thanks.