This is a partial reland of https://crrev.com/c/3597106 including fixes
from https://crrev.com/c/3654413

Before this change, a script cache key is the same format as an eval
cache key, which is a FixedArray containing:
- The SharedFunctionInfo of the containing function
- The source text
- The language mode in which the code was parsed
- The position in the source where eval was called

After this change, a script cache key is a WeakFixedArray containing:
- A weak pointer to the Script
- The hash value of the source text

This sets up for a subsequent change which can cause these keys to
outlive their corresponding values (top-level SharedFunctionInfos)
without leaking any memory beyond the key itself.

Bug: v8:12808
Change-Id: Ibdfe5d10eafe5b7392e554c500af47975baf45c6
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3668304Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Seth Brenith <seth.brenith@microsoft.com>
Cr-Commit-Position: refs/heads/main@{#80899}