bug#45554: [whishlist] Mathjax 3 / Google Closure Compiler

[Ricardo Wurmus <rekado@elephly.net>]

We should attempt to package Mathjax 3.  It is needed by a number of R
packages that cannot be upgraded due to the lack of MathjaxR, which
provides Mathjax 3 for R.

Mathjax is written in JavaScript.  Parts of it are written in
Typescript.  While I made some progress translating the Typescript parts
with esbuild, we still need to package

    https://github.com/zorkow/speech-rule-engine/

which is used by the accessibility modules of Mathjax and cannot easily
be skipped.

SRE needs the Google Closure Compiler (written in Java, with latest
versions requiring Bazel) and depends on three more JavaScript
libraries:

    https://github.com/zorkow/speech-rule-engine/blob/v3.1.1/package.json#L33

Of those I packaged Commander.js and xmldom-sre (not sure if they work,
because I’m ignorant of how node.js libraries are used);
wicked-good-xpath also requires the Google Closure Compiler.

So the next step appears to be to package an older pre-Bazel version of
Google Closure Compiler (and the associated Google Closure library), so
that we can build wicked-good-xpath and speech-rule-engine.

-- 
Ricardo