feat(g/emacs): Install dottime from depot via nix

To test out emacs package installs from depot

Change-Id: Ia8bb370d671c566c6ce8de08b47925ec3a1653e4
Reviewed-on: https://cl.tvl.fyi/c/depot/+/493
Reviewed-by: glittershark <grfn@gws.fyi>

users/glittershark/system/home/modules/lib/depot.nix

@@ -0,0 +1,5 @@
+{ config, lib, pkgs, ... }:
+
+{
+  lib.depot = import ~/code/depot {};
+}