📦 Created config files with common code

- Created common.nix for various configs
- Created theme.nix for theme related configs
- Moved some code to more logical files
- Moved some standalone files into nix multiline strings, in order to
  inject data

modules/gnome/default.nix

@@ -10,15 +10,13 @@
     glib
     adwaita-icon-theme
     gnomeExtensions.appindicator
-    #    gnome-extension-manager
+    # gnome-extension-manager
     loupe
     gnome-calculator
     gnome-disk-utility
   ];
 
-  programs = {
-    dconf.enable = true; # Required for some gnome applications
-  };
+  programs.dconf.enable = true; # Required for some gnome applications
 
   services = {
     gnome.gnome-keyring.enable = true;