This reverts commit 6ae18c2d.

Reason for revert: breaks a bunch of tests on Mac arm64 bots:

https://ci.chromium.org/ui/p/v8/builders/ci/V8%20Mac%20-%20arm64%20-%20release/5754/overview
https://ci.chromium.org/ui/p/v8/builders/ci/V8%20Mac%20-%20arm64%20-%20debug/2421/overview

Original change's description:
> [wasm] Move write scope out of NativeModule::AddCode
>
> {NativeModule::AddCode} is a central method that should usually be
> called in batches, where the caller holds a {CodeSpaceWriteScope} for a
> longer time (over several compilations).
> This CL moves us closer to that by removing the scope from that central
> method and instead putting it in callers where it becomes more visible.
> There are already TODOs to introduce caching or batching to avoid some
> switching, and one more TODO is added.
>
> Drive-by: Remove an unneeded {CodeSpaceMemoryModificationScope}.
>
> R=​jkummerow@chromium.org
>
> Bug: v8:11974
> Change-Id: Ia13c601abc766e5fca6ca053bf1fc4d647b53ed0
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3098186
> Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
> Commit-Queue: Clemens Backes <clemensb@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#76344}

Bug: v8:11974
Change-Id: Ia6a6814f153f7602d5d691bc5c930601ff4622a7
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3111268
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: Adam Klein <adamk@chromium.org>
Cr-Commit-Position: refs/heads/main@{#76414}