If used inside the NixOS/nix-darwin module, we get conflicting definitions
of `name` inside the specialization: one is the user name coming from the
NixOS module definition and the other is `configuration`, the name of this
option. Thus we need to explicitly wire the former into the module arguments.
See discussion at https://github.com/nix-community/home-manager/issues/3716
This module adds basic support for configuration specializations.
These allow the user to build multiple alternative configurations that
should be part of the same generation.