Also replace the schoolbook algorithm with an optimized version
that runs about twice as fast.
This also adds infrastructure to support interrupt checks from
BigInt library code.

Bug: v8:11515
Change-Id: I5f812913697384afca98937e1fb7361b4ec22d62
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2773043
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Reviewed-by: Thibaud Michaud <thibaudm@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74045}