This is a reland of 9701d4a4
with a small fix for some code landed in between the dry-run and
submission.

Original change's description:
> [base] Move most of src/numbers into base
>
> Moves all but conversions.*, hash-seed-inl.h and math-random.* into
> base, in preparation for moving the parts of conversions that don't
> access HeapObjects.
>
> Also moves uc16 and uc32 out of commons/globals.h into base/strings.h.
>
> Bug: v8:11917
> Change-Id: Ife359148bb0961a63833aff40d26331454b6afb6
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2979595
> Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
> Reviewed-by: Clemens Backes <clemensb@chromium.org>
> Commit-Queue: Ross McIlroy <rmcilroy@chromium.org>
> Auto-Submit: Dan Elphick <delphick@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#75354}

Bug: v8:11917
Change-Id: Ie1ec9032fe56646a7c7303185cecc70fce5694ae
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2982607Reviewed-by: Clemens Backes <clemensb@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Commit-Queue: Dan Elphick <delphick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#75368}