This uses Handle<WasmExceptionPackage> where applicable to increase type
safety. Note that {WasmExceptionPackage} is not a full-fledged instance
type though. The {HeapObject::IsWasmExceptionPackage} predicate is an
approximation because a precise version could only be implemented using
handlified code performing a property lookup.

R=clemensb@chromium.org

Change-Id: I061e3eea201a0e9909ba67ae33db81d14aaefe4b
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1477673
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Clemens Backes [né Hammacher] <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63987}