font handling in lualatex for chinese and math fonts.

[kmccurley]

it's a little unclear how fonts are handled in lualatex - I noticed when I compiled things from the command line that fonts were compiled and deposited in ~/.texlive2022 as compiled lua files, but these are not accessible when using --safer, so some characters get omitted. A good test case was provided to me by Ji Luo, who pointed at https://github.com/GeeLaw/ahbtr/paper I've been trying to figure out how to support Chinese, or at least simplified Chinese. It appears that we should be using the fontspec package with TTF fonts. Ideally we would pre-install those, maybe from the arphic-ttf package or the Noto Sans Simplified Chinese font.

[kmccurley]

We might also consider loading the fandol fonts for Simplified Chinese.

[jwbos]

Let me investigate this one.

[jwbos]

I don't think there is a problem. After some investigation it seems the best support for Chinese characters is using XeLaTeX. This font support can simply be enabled if the user then uses
\usepackage{xeCJK}
in their LaTeX sources. I tested this locally and writing to files, footer and author names work without any issue.

We need to add xecjk to the Dockerfile. I tested and everything seems to work.
I did not commit anything yet since xecjk seems to pull in a number of other packages and we need to update the supported packages page accordingly.