Major refactor to flake, abstract non-trivial packages into their own

files (such as firefox/spotify-qt+librespot), create utils for reusable
function library

nix/home/linux_aarch.nix

@@ -3,11 +3,13 @@
   ...
 }:
 {
+  imports = [
+    ./common/spotify_arm.nix
+  ];
+
   home = {
     packages = with pkgs; [
       legcord
-      librespot
-      spotify-qt
     ];
   };
 }