chore(tazjin/arbat): some more attempted fixes

* Try to convince libinput (seemingly futile) to change the trackpad behaviour.
* Make XFCE available to debug the EXWM hangs on this CPU.

Change-Id: Iff7189127c849beaf7ded3927abd14b90cf6b9fc
Reviewed-on: https://cl.tvl.fyi/c/depot/+/11775
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
Autosubmit: tazjin <tazjin@tvl.su>

users/tazjin/nixos/modules/desktop.nix

@@ -30,6 +30,7 @@
         name = "exwm";
         start = "${config.tazjin.emacs}/bin/tazjins-emacs --internal-border=0 --border-width=0";
       };
+      desktopManager.xfce.enable = true;
     };
   };