Operations on BigInts, for which TurboFan statically knows that they
are no larger than 2^64, can be lowered to efficient machine code
in TurboFan. This is the first step in doing so by generating
efficient code for asUintN and the required checks and conversions.

Bug: v8:9407
Change-Id: I51f6505f6c4567434fa369fcf870a09871487f51
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1680548
Commit-Queue: Nico Hartmann <nicohartmann@google.com>
Reviewed-by: Georg Neis <neis@chromium.org>
Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62488}