Use ICU64 new API formatStringsToValue

Bug: v8:8836
Change-Id: I7399a301b2536f331b1df1e1845adf2e533bafb9
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1560659
Commit-Queue: Frank Tang <ftang@chromium.org>
Reviewed-by: Sathya Gunasekaran <gsathya@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60856}