This CL adds support for BigInt.asIntN, the necessary operations and
extensions of the compiler's type system to allow lowering of BigInts
to word64 representations that are interpreted as signed 64 bit BigInts.

Bug: v8:9407
Change-Id: Id4f1f45437c1caf94e01c7b4e063c2ae2386c88a
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3198070
Commit-Queue: Nico Hartmann <nicohartmann@chromium.org>
Reviewed-by: Maya Lekova <mslekova@chromium.org>
Cr-Commit-Position: refs/heads/main@{#77458}