This is a reland of 81dd3f42,
which was a reland of 59eff3bf

Original change's description:
> [bigint] Karatsuba multiplication
>
> The Karatsuba algorithm is used for BigInts with 34 or more internal
> digits, and thanks to better asymptotic complexity provides greater
> speedups the bigger the inputs.
>
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2782283
> Reviewed-by: Michael Achenbach <machenbach@chromium.org>
> Reviewed-by: Thibaud Michaud <thibaudm@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#74916}

Bug: v8:11515
Change-Id: I08f7d59dfa39fb3b532684685afd9fa750e0e84e
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2933666Reviewed-by: Clemens Backes <clemensb@chromium.org>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74969}