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.
According to https://endoflife.software/programming-languages/server-side-scripting/ruby
ruby 2.4 will go end-of-life in march, where the new release of nixpkgs
will be cut. We won't be able to support it for security updates.
Remove all references to ruby_2_4 and add ruby_2_7 instead where
missing.
Mark packages that depend on ruby 2.4 as broken:
* chefdk
* sonic-pi
