Embedders must override the method, because returning a nullptr will
make V8 crash. Hence the method should be abstract.

Bug: v8:12425
Change-Id: I79e1759acd2a5f41424145637ee1fbd161889ec1
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3779694Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82058}