nixos/htop: add module

This module allows setting global configuration for htop in /etc/htoprc,

for example to disable showing userland threads by default

Co-authored-by: pennae <82953136+pennae@users.noreply.github.com>

Co-authored-by: Aaron Andersen <aaron@fosslib.net>

nixos/modules/module-list.nix

@@ -154,6 +154,7 @@
   ./programs/gnupg.nix
   ./programs/gphoto2.nix
   ./programs/hamster.nix
+  ./programs/htop.nix
   ./programs/iftop.nix
   ./programs/iotop.nix
   ./programs/java.nix