[Fizz] Support aborting with Postpone (#28183)

Semantically if you make your reason for aborting a Postpone instance
the render should not hit the error pathways but should instead follow
the postpone pathways. It's awkward today to actually get your hands on
a Postpone instance because you have to catch the throw from postpone
and then pass that into `abort()` or `AbortController.abort()`
(depending on the renderer API you are using)

This change makes it so that in most circumstances if you abort with a
postpone the `onPostpone` handler will be called and the Suspense
boundaries still pending will be put into client render mode with the
appropriate postpone digest to avoid trigger recoverable error pathways
on the client.

Similar to postponing in the shell during a resume or render however if
you abort before the shell is complete in a resume or render we will
fatally error. The fatal error is contextualized by React to avoid
passing the postpone object itself to the `onError` and related options.

scripts/error-codes/codes.json

@@ -485,5 +485,6 @@
   "497": "Only objects or functions can be passed to taintObjectReference.",
   "498": "Only plain objects, and a few built-ins, can be passed to Client Components from Server Components. Classes or null prototypes are not supported.",
   "499": "Only plain objects, and a few built-ins, can be passed to Server Actions. Classes or null prototypes are not supported.",
-  "500": "React expected a headers state to exist when emitEarlyPreloads was called but did not find it. This suggests emitEarlyPreloads was called more than once per request. This is a bug in React."
+  "500": "React expected a headers state to exist when emitEarlyPreloads was called but did not find it. This suggests emitEarlyPreloads was called more than once per request. This is a bug in React.",
+  "501": "The render was aborted with postpone when the shell is incomplete. Reason: %s"
 }