[Overlays+Packages] Move unstable + nur overlays into package/unstable.nix

packages/unstable.nix

@@ -0,0 +1,28 @@
+{ config, pkgs, lib, ... }:
+with lib;
+let
+  cfg = config.aviallon.overlays;
+  hardwareCfg = config.aviallon.hardware;
+  unstable = import (fetchGit {
+    url = "https://github.com/NixOS/nixpkgs.git";
+    ref = "nixos-unstable";
+  }) {
+    config = config.nixpkgs.config // { allowUnfree = true; } ;
+    overlays = config.nixpkgs.overlays;
+  };
+  nur = import (fetchGit {
+    url = "https://github.com/nix-community/NUR.git";
+    ref = "master";
+  }) {
+    inherit pkgs;
+  };
+in {
+  config = {
+    nixpkgs.overlays = mkBefore ([]
+      ++ [(final: prev: {
+        inherit nur;
+        inherit unstable;
+      })]
+    );
+  };
+}