Add Preview namespace to EE extension so Rails

could find it better?

app/mailers/previews/notify_preview.rb

 class NotifyPreview < ActionMailer::Preview
-  prepend EE::NotifyPreview
+  prepend EE::Preview::NotifyPreview
 
   def note_merge_request_email_for_individual_note
     note_email(:note_merge_request_email) do

ee/app/mailers/ee/preview/notify_preview.rb

 module EE
+  module Preview
     module NotifyPreview
       extend ActiveSupport::Concern
 
@@ -56,4 +57,5 @@ module EE
         @user ||= User.first
       end
     end
+  end
 end