improvement: sort relationship in order of input when managing it

This helps with things like https://github.com/ash-project/ash_phoenix/issues/57
which involve rendering the relationship value after editing it. Retaining
the order allows direct reuse without any gymnastics

lib/ash/actions/managed_relationships.ex

@@ -645,6 +645,13 @@ defmodule Ash.Actions.ManagedRelationships do
                opts
              ) do
           {:ok, new_value, notifications} ->
+            new_value =
+              if is_list(new_value) do
+                Enum.reverse(new_value)
+              else
+                new_value
+              end
+
             {:ok, Map.put(record, relationship.name, new_value),
              all_notifications ++ notifications}
 

test/actions/create_test.exs

@@ -580,11 +580,11 @@ defmodule Ash.Test.Actions.CreateTest do
         |> Api.create!()
         |> strip_metadata()
 
-      assert Enum.sort(post.related_posts) ==
-               Enum.sort([
+      assert post.related_posts ==
+               [
                  Api.get!(Post, post2.id),
                  Api.get!(Post, post3.id)
-               ])
+               ]
                |> strip_metadata()
     end
   end