dillon1000/react

Formalize the Wakeable and Thenable types (#18391)

* Formalize the Wakeable and Thenable types

We use two subsets of Promises throughout React APIs. This introduces
the smallest subset - Wakeable. It's the thing that you can throw to
suspend. It's something that can ping.

I also use a shared type for Thenable in the cases where we expect a value
so we can be a bit more rigid with our us of them.

* Make Chunks into Wakeables instead of using native Promises

This value is just going from here to React so we can keep it a lighter
abstraction throughout.

* Renamed thenable to wakeable in variable names