Track ThenableState alongside other hooks

Now that hook state is preserved while the work loop is suspended, we
don't need to track the thenable state in the work loop. We can track
it alongside the rest of the hook state.

This is a nice simplification and also aligns better with how it works
in Fizz and Flight.

The promises will still be cleared when the component finishes rendering
(either complete or unwind). In the future, we could stash the promises
on the fiber and reuse them during an update. However, this would only
work for `use` calls that occur before an prop/state/context is
processed, because `use` calls can only be assumed to execute in the
same order if no other props/state/context have changed. So it might not
be worth doing until we have finer grained memoization.

scripts/error-codes/codes.json

@@ -446,5 +446,6 @@
   "458": "Currently React only supports one RSC renderer at a time.",
   "459": "Expected a suspended thenable. This is a bug in React. Please file an issue.",
   "460": "Suspense Exception: This is not a real error! It's an implementation detail of `use` to interrupt the current render. You must either rethrow it immediately, or move the `use` call outside of the `try/catch` block. Capturing without rethrowing will lead to unexpected behavior.\n\nTo handle async errors, wrap your component in an error boundary, or call the promise's `.catch` method and pass the result to `use`",
-  "461": "This is not a real error. It's an implementation detail of React's selective hydration feature. If this leaks into userspace, it's a bug in React. Please file an issue."
+  "461": "This is not a real error. It's an implementation detail of React's selective hydration feature. If this leaks into userspace, it's a bug in React. Please file an issue.",
+  "462": "Unexpected SuspendedReason. This is a bug in React."
 }