[bug#63604] Branch "tex-team-next" in need of review

[Nicolas Goaziou <mail@nicolasgoaziou.fr>]

Hello,

The "tex-team-next" branch has reached a milestone, so I started the
process of merging it into "master".

In a nutshell, this branch provides:

 - TeX Live 2023 ;

 - more packages, including some collections and schemes ;

 - a beefed-up importer : it handles most native inputs and arguments.
   It can also produce meta-packages ;

 - normalized package names and definitions : no more
   `simple-texlive-package', only a limited set of Guix specific
   packages, described in a comment at the beginning of the module ;

 - a more voluntary build system : it can generate runfiles, build font
   metrics, generate TeX formats, and install scripts ;

 - a lighter `texlive-bin' : it no longer provides every TeX Live script
   right from the start, reducing (!) the number of files added to
   "bin/" from 400 to 200 ;

 - an actually usable modular TeX Live, with no more hyphenation issues,
   and less packages to list thanks to collections.

Adding new packages is very easy, but they still have to be updated
manually every time we bump TeX Live version. It would be nice to buy us
an updater at some point.

I also think we can further modularize `texlive-bin': some binaries may
be built along with their respective texlive package instead. Food for
thoughts.

Regards,
-- 
Nicolas Goaziou