Android: Read CCT client package name via identity sharing

CCT adopts a new API returning calling activity's package name.

Low-Coverage-Reason: Android U bot to test this on not available yet

Bug: 1425229
Change-Id: I9e51462650dcf622fb01d3e7431db237245cc530
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4348232


Reviewed-by: Theresa Sullivan <twellington@chromium.org>
Commit-Queue: Jinsuk Kim <jinsukkim@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1118878}