budgie-session: move from budgie scope to top-level

nixos/modules/services/x11/desktop-managers/budgie.nix

@@ -126,7 +126,7 @@ in {
         (budgie-desktop-with-plugins.override { plugins = cfg.extraPlugins; })
         budgie-desktop-view
         budgie-screensaver
-        budgie.budgie-session
+        budgie-session
 
         # Required by Budgie Menu.
         gnome-menus

pkgs/desktops/budgie/default.nix

@@ -6,7 +6,6 @@ lib.makeScope newScope (
     inherit (self) callPackage;
   in
   {
-    budgie-session = callPackage ./budgie-session { };
     magpie = callPackage ./magpie { };
   }
 )