dillon1000/react

[Fizz] Start initial work immediately (#31079)

In a recent update we make Flight start working immediately rather than
waitin for a new task. This commit updates fizz to have similar
mechanics. We start the render in the currently running task but we do
so in a microtask to avoid reentrancy. This aligns Fizz with Flight.

ref: https://github.com/facebook/react/pull/30961