This is a reland of commit c2f25454.
We revert to using x17 for the call target, to be compliant with CFI.
Some comments are extended to point to that requirement.

Original change's description:
> Avoid use of x18 register on arm64
>
> This causes crashes on Windows, as x18 is the "platform register",
> holding a pointer to thread-local storage.
>
> R=jkummerow@chromium.org
> CC=seth.brenith@microsoft.com
>
> Bug: v8:12959
> Change-Id: I20b8bee145d4ab3a40d8d140d98572df8300251c
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3695569
> Reviewed-by: Seth Brenith <seth.brenith@microsoft.com>
> Commit-Queue: Clemens Backes <clemensb@chromium.org>
> Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#81090}

Bug: v8:12959
Change-Id: If4ead8f7a7aece756cef7d32bb98d7d33dfe4911
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3702331Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Reviewed-by: Seth Brenith <seth.brenith@microsoft.com>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/main@{#81111}