Fixed backward FieldBuilder methods. (#662)

Co-authored-by: John Fredrickson <john.fredrickson@arinet.com>

backend/src/Squidex.Domain.Apps.Entities/Apps/Templates/Builders/FieldBuilder.cs

@@ -64,16 +64,16 @@ namespace Squidex.Domain.Apps.Entities.Apps.Templates.Builders
 
         public FieldBuilder ShowInList()
         {
-            schema.FieldsInReferences ??= new FieldNames();
+            schema.FieldsInLists ??= new FieldNames();
-            schema.FieldsInReferences.Add(field.Name);
+            schema.FieldsInLists.Add(field.Name);
 
             return this;
         }
 
         public FieldBuilder ShowInReferences()
         {
-            schema.FieldsInLists ??= new FieldNames();
+            schema.FieldsInReferences ??= new FieldNames();
-            schema.FieldsInLists.Add(field.Name);
+            schema.FieldsInReferences.Add(field.Name);
 
             return this;
         }