Add ability to list users

lib/mobilizon_web/schema/sort.ex

@@ -0,0 +1,9 @@
+defmodule MobilizonWeb.Schema.SortType do
+  use Absinthe.Schema.Notation
+
+  @desc "Available sort directions"
+  enum :sort_direction do
+    value(:asc)
+    value(:desc)
+  end
+end