dillon1000/react

[Fizz] Add FormatContext and Refactor Work (#21103)

* Add format context

* Let the Work node hold all working state for the recursive loop

Stacks are nice and all but there's a cost to maintaining each frame
both in terms of stack size usage and writing to it.

* Move current format context into work

* Synchronously render children of a Suspense boundary

We don't have to spawn work and snapshot the context. Instead we can try
to render the boundary immediately in case it works.

* Lazily create the fallback work

Instead of eagerly create the fallback work and then immediately abort it.
We can just avoid creating it if we finish synchronously.