📦 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/hardware/graphics/nvidia.nix

@@ -1,5 +1,3 @@
-{ ... }:
-
 {
   hardware.nvidia = {
     # Required