Realistically I want access to htop on any machine running my shell
configuration. Making this NixOS-specific removes some of the dependence
on home-manager as well.
Although many people have tried to make more modern top-like programs,
my favorite is still htop *by far*. NixOS includes htop-vim in its
official repositories, which is great, and this change removes the
/nix/store prefixes from all the processes, making htop overall much
easier to read and navigate.