Fix: Update selection in shapekey dopesheet

Shift+LMB selection in tree view doesn't update selection state in
shapekey dopesheet. To fix this, add notifier for area redraw.
In other cases, `on_activate()` function of inherited class handles
the notifier.

Pull Request: https://projects.blender.org/blender/blender/pulls/141543

source/blender/editors/interface/interface_ops.cc

@@ -2827,6 +2827,7 @@ static wmOperatorStatus ui_view_item_select_invoke(bContext *C,
         item.set_selected(true);
       }
     });
+    WM_main_add_notifier(NC_ANIMATION, nullptr);
     return OPERATOR_FINISHED;
   }