pantheon: stylize expressions

The same way we want them in GNOME in nixpkgs.
Didn't touch the greeter expression because I have
a branch where it's already rewritten.

pkgs/desktops/pantheon/apps/switchboard/wrapper.nix

@@ -1,4 +1,9 @@
-{ makeWrapper, symlinkJoin, switchboard, switchboardPlugs, plugs }:
+{ makeWrapper
+, symlinkJoin
+, switchboard
+, switchboardPlugs
+, plugs
+}:
 
 let
   selectedPlugs = if plugs == null then switchboardPlugs else plugs;