* gnome3: only maintain single GNOME 3 package set
GNOME 3 was split into 3.10 and 3.12 in #2694. Unfortunately, we barely have the resources
to update a single version of GNOME. Maintaining multiple versions just does not make sense.
Additionally, it makes viewing history using most Git tools bothersome.
This commit renames `pkgs/desktops/gnome-3/3.24` to `pkgs/desktops/gnome-3`, removes
the config variable for choosing packageset (`environment.gnome3.packageSet`), updates
the hint in maintainer script, and removes the `gnome3_24` derivation from `all-packages.nix`.
Closes: #29329
* maintainers/scripts/gnome: Use fixed GNOME 3 directory
Since we now allow only a single GNOME 3 package set, specifying
the working directory is not necessary.
This commit sets the directory to `pkgs/desktops/gnome-3`.
Using pkgs.lib on the spine of module evaluation is problematic
because the pkgs argument depends on the result of module
evaluation. To prevent an infinite recursion, pkgs and some of the
modules are evaluated twice, which is inefficient. Using ‘with lib’
prevents this problem.
