A generalization of Karatsuba's idea for even larger inputs.

Bug: v8:11515
Change-Id: I50eac2d313bf4217bf2f55ca2e64b5f120f40206
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2999870
Auto-Submit: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Reviewed-by: Maya Lekova <mslekova@chromium.org>
Cr-Commit-Position: refs/heads/master@{#75598}