This CL moves SharedFunctionInfo and BytecodeArray to the
kNeverSerialized classes, making them directly accessible from the
background thread.

To resolve the dependence on HeapNumber and BigInt objects stored in
the BytecodeArray's constant pool, this CL introduces a new
ObjectDataKind::kPossiblyBackgroundSerializedHeapObject, which allows
for objects to be serialized lazily from the background thread where
we know that this is safe (e.g. because they are constant). BigInt and
HeapNumber are the first members of this new group of objects.

Bug: v8:7790
Change-Id: I1d962d1cb7c36cc3f5baeb9603d5298f32af3363
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2567705Reviewed-by: Georg Neis (ooo until January 5) <neis@chromium.org>
Commit-Queue: Nico Hartmann <nicohartmann@chromium.org>
Cr-Commit-Position: refs/heads/master@{#71716}