continuation of #109595
pkgconfig was aliased in 2018, however, it remained in
all-packages.nix due to its wide usage. This cleans
up the remaining references to pkgs.pkgsconfig and
moves the entry to aliases.nix.
python3Packages.pkgconfig remained unchanged because
it's the canonical name of the upstream package
on pypi.
Fixes various security bugs with CVEs since 2017.
Fixes#73645.
Note that for 1.3.6 *ONLY*, the file was called `graphite-*.tgz`
and not `graphite2-*.tgz`, that's why the URL changes as well.
Kept the old hacks where they don't break the build in case they things
they fix are still relevant.
I checked that the upgrade doesn't break:
1) Asymptote and EProver builds.
2) My XeLaTeX demo from configurations/ repository.
3) Some of my own files.
The upgrade fixes problems with simultaneous use of 3D and LaTeX labels
in Asymptote.
Please provide a test that worked previously and is broken now if you
need to revert this update or its parts.