Do a full copy of all fields when initialising and copying from the
placeholder SharedFunctionInfo that is used in off-thread function
compilation. This guarantees that all fields are correct both in the
on-thread and off-thread cases.

Change-Id: If1807c6f56fe38fea40ed39596f85634356e2623
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3260518Reviewed-by: Victor Gomes <victorgomes@chromium.org>
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/main@{#77720}