[WebView] (3) Add integration test {All hints}

This is the second to last test, and it verifies all existing client
hints and makes sure that any new additions get verified as well. The
final test will be for the CRITICAL-CH system.

This CL is part of a series:
(1) Add scaffolding for persistent client hints
(2) Implement AwClientHintsControllerDelegate {...}
(3) Add integration test {...}
(4) Enable persistent client hints by default

Design doc:
https://docs.google.com/document/u/1/d/1r1AKHex1_UKh3wIp4ITkU4-J9-tdNZSOmUDeDVWw_AU/edit

Bug: 921655
Change-Id: I88dff3087f2f7579afa63612e90a1ed76249abd5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4087543
Auto-Submit: Ari Chivukula <arichiv@chromium.org>
Reviewed-by: Richard Coles <torne@chromium.org>
Commit-Queue: Ari Chivukula <arichiv@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1081096}