Support colored emojis in PDF output

[Peque]

As of #22, there is support for black and white emojis, but the Symbola font does not display all emojis properly (i.e.: modifiers are not applied). It would be great to support colored emojis.

Twemoji should be preferred over Noto, since that is what we are already allowing in the HTML builds.

See:

• https://tex.stackexchange.com/questions/497403/how-to-use-noto-color-emoji-with-lualatex
• https://ctan.org/pkg/twemoji-colr
• https://ctan.org/pkg/noto-emoji

Ideally, it should be easy to run/reproduce from current Linux distributions without requiring much effort on the user side.

The font must be free/libre though.

[ypapouin]

For information, there is a now a dedicated package for the lua(la)tex engine

\usepackage{emoji}

https://github.com/stone-zeng/latex-emoji
https://mirrors.mit.edu/CTAN/macros/luatex/latex/emoji/emoji-doc.pdf

That means that a pre-processor should be made to translate both:

• |:snake:| -> \emoji{snake}
• 🐍 -> \emoji{snake}

The mapping tables could be parsed and used to automatically generate this rst -> latex pre-processor

• https://github.com/stone-zeng/latex-emoji/blob/main/emoji-table.def
• https://github.com/sphinx-contrib/emojicodes/blob/master/sphinxemoji/codes.json