Sort custom fields by name as default in read action

Add `prepare build(sort: [name: :asc])` to the primary read action of
CustomField. Prevents order changes when toggling the `required` flag.

lib/membership/custom_field.ex

@@ -52,7 +52,8 @@ defmodule Mv.Membership.CustomField do
   use Ash.Resource,
     domain: Mv.Membership,
     data_layer: AshPostgres.DataLayer,
-    authorizers: [Ash.Policy.Authorizer]
+    authorizers: [Ash.Policy.Authorizer],
+    primary_read_warning?: false
 
   postgres do
     table "custom_fields"
@@ -60,9 +61,13 @@ defmodule Mv.Membership.CustomField do
   end
 
   actions do
-    defaults [:read]
     default_accept [:name, :value_type, :description, :required, :show_in_overview]
 
+    read :read do
+      primary? true
+      prepare build(sort: [name: :asc])
+    end
+
     create :create do
       accept [:name, :value_type, :description, :required, :show_in_overview]
       change Mv.Membership.Changes.GenerateSlug