dillon1000/react

[Fiber] Trigger default transition indicator if needed (#33160)

Stacked on #33159.

This implements `onDefaultTransitionIndicator`.

The sequence is:

1) In `markRootUpdated` we schedule Transition updates as needing
`indicatorLanes` on the root. This tracks the lanes that currently need
an indicator to either start or remain going until this lane commits.
2) Track mutations during any commit. We use the same hook that view
transitions use here but instead of tracking it just per view transition
scope, we also track a global boolean for the whole root.
3) If a sync/default commit had any mutations, then we clear the
indicator lane for the `currentEventTransitionLane`. This requires that
the lane is still active while we do these commits. See #33159. In other
words, a sync update gets associated with the current transition and it
is assumed to be rendering the loading state for that corresponding
transition so we don't need a default indicator for this lane.
4) At the end of `processRootScheduleInMicrotask`, right before we're
about to enter a new "event transition lane" scope, it is no longer
possible to render any more loading states for the current transition
lane. That's when we invoke `onDefaultTransitionIndicator` for any roots
that have new indicator lanes.
5) When we commit, we remove the finished lanes from `indicatorLanes`
and once that reaches zero again, then we can clean up the default
indicator. This approach means that you can start multiple different
transitions while an indicator is still going but it won't stop/restart
each time. Instead, it'll wait until all are done before stopping.

Follow ups:

- [x] Default updates are currently not enough to cancel because those
aren't flush in the same microtask. That's unfortunate. #33186
- [x] Handle async actions before the setState. Since these don't
necessarily have a root this is tricky. #33190
- [x] Disable for `useDeferredValue`. ~Since it also goes through
`markRootUpdated` and schedules a Transition lane it'll get a default
indicator even though it probably shouldn't have one.~ EDIT: Turns out
this just works because it doesn't go through `markRootUpdated` when
work is left behind.
- [x] Implement built-in DOM version by default. #33162