lxde: refactor

To be more in line with the other desktops. Indeed it is strange to look at all
those lxde packages spread over all-packages.nix.

pkgs/desktops/lxde/default.nix

···
+{ config, lib, pkgs }:
+
+lib.makeScope pkgs.newScope (self: with self; {
+
+  lxappearance = callPackage ./core/lxappearance { };
+
+  lxappearance-gtk2 = callPackage ./core/lxappearance {
+    gtk2 = gtk2-x11;
+    withGtk3 = false;
+  };
+
+  lxmenu-data = callPackage ./core/lxmenu-data { };
+
+  lxpanel = callPackage ./core/lxpanel {
+    gtk2 = gtk2-x11;
+  };
+
+  lxrandr = callPackage ./core/lxrandr { };
+
+  lxsession = callPackage ./core/lxsession { };
+
+  lxtask = callPackage ./core/lxtask { };
+})

pkgs/top-level/all-packages.nix

···
 
   ### DESKTOPS/LXDE
 
-  lxappearance = callPackage ../desktops/lxde/core/lxappearance { };
-
-  lxappearance-gtk2 = callPackage ../desktops/lxde/core/lxappearance {
-    gtk2 = gtk2-x11;
-    withGtk3 = false;
-  };
-
-  lxmenu-data = callPackage ../desktops/lxde/core/lxmenu-data.nix { };
-
-  lxpanel = callPackage ../desktops/lxde/core/lxpanel {
-    gtk2 = gtk2-x11;
-  };
-
-  lxrandr = callPackage ../desktops/lxde/core/lxrandr { };
-
-  lxsession = callPackage ../desktops/lxde/core/lxsession { };
-
-  lxtask = callPackage ../desktops/lxde/core/lxtask { };
+  lxde = recurseIntoAttrs (callPackage ../desktops/lxde { });
+  # Backwards compatibility aliases
+  inherit (lxde)
+    lxappearance
+    lxappearance-gtk2
+    lxmenu-data
+    lxpanel
+    lxrandr
+    lxsession
+    lxtask
+  ;
 
   lxqt = recurseIntoAttrs (import ../desktops/lxqt {
     inherit pkgs;