Design editor: layer reorder is lost when binding a parent group to a product list

**Bug** In the design editor, when a user: 1. Creates a group/parent layer containing child layers (a parent of one or more layers) 2. Drags the child layers into a different order 3. Then creates a data link binding that parent group to a product list ...the product list renders using the **old** layer order instead of the reordered one. **Expected:** The reordered layer sequence should be preserved and used when the parent is bound to a product list. **Actual:** The original (pre-drag) order is shown after the data link is created. Likely the reorder isn't being persisted to the layer tree (or is being overwritten) before the product-list binding snapshots the child order.