Having to change the package list in two places was a bit redundant. We
can also use `with` patterns now since nixd warns if there are escaping
variables being used.
Note that variables used in multiple places are kept to make it easier
to recognize that those variables must be changed together. Also note
that inherit (pkgs) inside of mkMerge are currently kept to reduce the
diff.
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.
