* Add Event Replaying Infra
* Wire up Roots and Suspense boundaries, to retry events, after they commit
* Replay discrete events in order in a separate scheduler callback
* Add continuous events
These events only replay their last target if the target is not yet
hydrated. That way we don't have to wait for a previously hovered
boundary before invoking the current target.
* Enable tests from before
These tests were written with replaying in mind and now we can properly
enable them.
* Unify replaying and dispatching
* Mark system flags as a replay and pass to legacy events
That way we can check if this is a replay and therefore needs a special
case. One such special case is "mouseover" where we check the
relatedTarget.
* Eagerly listen to all replayable events
To minimize breakages in a minor, I only do this for the new root APIs
since replaying only matters there anyway. Only if hydrating.
For Flare, I have to attach all active listeners since the current
system has one DOM listener for each. In a follow up I plan on optimizing
that by only attaching one if there's at least one active listener
which would allow us to start with only passive and then upgrade.
* Desperate attempt to save bytese
* Add test for mouseover replaying
We need to check if the "relatedTarget" is mounted due to how the old
event system dispatches from the "out" event.
* Fix for nested boundaries and suspense in root container
This is a follow up to #16673 which didn't have a test because it wasn't
observable yet. This shows that it had a bug.
* Rename RESPONDER_EVENT_SYSTEM to PLUGIN_EVENT_SYSTEM
