Provide a stub `third_party_heap::Heap` implementation to work around
linker erors with Visual Studio.

Refs: https://github.com/bnoordhuis/v8-cmake/pull/50
Bug: v8:10427
Change-Id: I435081d8cb195d1db999db699df3d3751663c81d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3366367Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/main@{#78587}