Add support for distinct sort tests

Author: ken-kost

test/support/resources/comment.ex

@@ -69,6 +69,8 @@ defmodule AshPostgres.Test.Comment do
          "hello"
        end)}
     end)
+
+    calculate(:double_likes, :integer, expr((likes || 0) * 2))
   end
 
   relationships do

test/support/resources/post.ex

@@ -673,6 +673,18 @@ defmodule AshPostgres.Test.Post do
       public?(true)
     end
 
+    has_one :most_liked_comment, AshPostgres.Test.Comment do
+      sort(likes: :desc)
+      from_many?(true)
+      public?(true)
+    end
+
+    has_one :most_popular_comment, AshPostgres.Test.Comment do
+      sort(double_likes: :desc)
+      from_many?(true)
+      public?(true)
+    end
+
     has_many :comments_matching_post_title, AshPostgres.Test.Comment do
       public?(true)
       filter(expr(title == parent_expr(title)))