Change to use Handle<Object> instead of Handle<String>
for calendar and offset_string.

Spec text:
https://tc39.es/proposal-temporal/#sec-temporal-torelativetemporalobject

Bug: v8:11544
Change-Id: Ia9051f176e0e91a362b0c6b9edf6fea5a53ddcf2
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3808256Reviewed-by: Adam Klein <adamk@chromium.org>
Commit-Queue: Frank Tang <ftang@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82363}