Closes bevyengine#3329

`parent_update` and `transform_propagate` run in the same stage but `parent_update` can spawn `Children`. This means that the `system` can enter an inconsistent state where the `GlobalTransform` has not been updated on `Children` when spawning an `Entity` where the `Parent` does not have an existing `Children` component.

Introduce a marker trait, `DirtyParent`, so that the system will revert to the correct state the next time the systems run.

crates/bevy_hierarchy/src/components/parent.rs

@@ -62,3 +62,6 @@ impl FromWorld for PreviousParent {
         PreviousParent(Entity::from_raw(u32::MAX))
     }
 }
+
+#[derive(Component, Debug, Copy, Clone, Eq, PartialEq, Reflect)]
+pub struct DirtyParent;