This is a reland of commit 0a1f0e33

Changes since revert:
- Deferred label for loading from forwarding table.
- Check if hash is computed instead of checking if it is a forwarding index.
- Retreive hash from forwarding table only if hash is assumed to be computed.

Original change's description:
> [strings] Fix raw hash lookup for forwarded strings
>
> Raw hashes may need to be looked up via the forwarding table when
> internalized strings are forwarded to external resources. Notably, the
> megamorphic ICs were not correctly fetching the raw hash.
>
> Bug: v8:12007
> Change-Id: Ibbc75de57e707788f544fbd1a0f8f0041350e29d
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3885379
> Reviewed-by: Leszek Swirski <leszeks@chromium.org>
> Commit-Queue: Shu-yu Guo <syg@chromium.org>
> Reviewed-by: Patrick Thier <pthier@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#83115}

Bug: v8:12007
Change-Id: Ia88ed51a49c62170bc960b8f69673bb1e59a6009
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3888057
Commit-Queue: Patrick Thier <pthier@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/main@{#83246}