Implement the ECMA402 localeMatcher: "best fit" option
by using ICU LocaleMatcher API.

Bug: v8:7051
Change-Id: I3d7c1ee39a5c649a5f500429f2b41329346a1a78
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1943050Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Frank Tang <ftang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65507}