Handle the pattern 'c' return by ICU in Intl.DateTimeFormat
for weekday standalone form.
Add regression test to ensure all the standalone pattern return
option are in the expected list.

Bug: v8:8413
Change-Id: I9ab42383e3882ef1720606830624775e2748fccb
Reviewed-on: https://chromium-review.googlesource.com/c/1318092Reviewed-by: Jungshik Shin <jshin@chromium.org>
Reviewed-by: Sathya Gunasekaran <gsathya@chromium.org>
Commit-Queue: Frank Tang <ftang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57299}