dillon1000/react

Fix: Hide new/updated nodes in already hidden tree (#21929)

When a new node is added to an already hidden Offscreen tree, we need
to schedule a visibility effect to hide it. Previously we would only
hide when the boundary initially switches from visible to hidden, which
meant that newly inserted nodes would be visible.

We need to do the same thing for nodes that are updated, because the
update might affect the DOM node's `style.display` property.

The implementation is to check the `subtreeFlags` for an Insertion or
Update effect.

This only affects Offscreen, not Suspense, because Suspense boundaries
cannot be updated while in their fallback (hidden) state.

And it only affects mutation mode, because in persistent mode we
implement hiding by cloning the host tree during the complete phase,
which already happens on every update.