📦 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/default.nix

@@ -1,5 +1,3 @@
-{ ... }:
-
 {
   imports = [
     ./development.nix
@@ -15,5 +13,6 @@
     ./steam.nix
     ./stylix.nix
     ./terminal
+    ./qt.nix
   ];
 }