[Doc]: make html fail early if latex not present

[jamesbraza]

Documentation Link

https://matplotlib.org/devdocs/devel/documenting_mpl.html#building-the-docs

Problem

If you don't have LaTeX installed, make html will fail about 5-mins in. I then came upon this (from here):

Required:

• a minimal working LaTeX distribution

I think it would be a nice feature to deny make html without a LaTeX being present.

Suggested improvement

Have the doc/Makefile's make html recipe have a "guard" mechanism that, if LaTeX isn't installed, errors with:

LaTeX is required for this command.

This could also be a good sister solution to #24646, where the guard behavior checks the LaTeX installation works and has the required packages installed.

[story645]

part of implementing this would be adding the sort of checks that #24414 would require and I also think this would be good as a standalone.