core: Enable resize for GUI layer duplication

Resolves #13633 (for now)
Same rationale as 975d1a4a, as diagnosed by Thomas Manni.

During 3.2 development, we can review and likely just set this as
the default value inside GimpDrawable.
For now, this is a limited bugfix for 3.0.x.

app/actions/layers-commands.c

@@ -832,6 +832,7 @@ layers_duplicate_cmd_callback (GimpAction *action,
                             gimp_layer_get_parent (iter->data),
                             gimp_item_get_index (iter->data),
                             TRUE);
+      gimp_drawable_enable_resize_undo (GIMP_DRAWABLE (new_layer));
       new_layers = g_list_prepend (new_layers, new_layer);
 
       /* Import any attached layer effects */