Embedders often use integers for representing scriptIds, but the
stack trace interface only exposes scriptIds as strings, which
introduces the need for parsing the scriptId string to an int in
the embedder.

This CL also exposes the scriptId as an integer.

Bug: chromium:1158782
Change-Id: I7d85ad1497f2eff17f5cd8f9c87f0c72696c1ecf
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2589973
Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#71761}