Fix #125270: Outliner: Fade child object linked to other collection

In Outliner dim children that are linked to other collections.

Pull Request: https://projects.blender.org/blender/blender/pulls/133637

source/blender/editors/space_outliner/outliner_draw.cc

@@ -3271,7 +3271,8 @@ static bool element_should_draw_faded(const TreeViewContext &tvc,
                                (const Base *)te->directdata :
                                BKE_view_layer_base_find((ViewLayer *)tvc.view_layer, (Object *)ob);
         const bool is_visible = (base != nullptr) &&
-                                (base->flag & BASE_ENABLED_AND_VISIBLE_IN_DEFAULT_VIEWPORT);
+                                (base->flag & BASE_ENABLED_AND_VISIBLE_IN_DEFAULT_VIEWPORT) &&
+                                !BLI_listbase_is_empty(&te->subtree);
 
         return !is_visible;
       }