Due to streaming, the SFI enqueueing can happen concurrently with with
main-thread finalising, so we need to add locks around accesses to the
SFI->Job map.

Bug: v8:12370
Change-Id: I60281a954ef10f7fcde559b9529077a6b9a82c31
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3277874
Auto-Submit: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Victor Gomes <victorgomes@chromium.org>
Reviewed-by: Victor Gomes <victorgomes@chromium.org>
Cr-Commit-Position: refs/heads/main@{#77869}