[Site data] Add confirmation dialog to block site data

Add a confirmation dialog that's shown when a user blocks site data. On
confirmation the setting is committed. On cancelling the settings is not
committed.

Bug: 1378703
Change-Id: Ia0e7d14acd6b2bc404c9f9c0c4eda6fb213d9807
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4127437
Reviewed-by: Olesia Marukhno <olesiamarukhno@google.com>
Auto-Submit: Rainhard Findling <rainhard@chromium.org>
Reviewed-by: Theodore Olsauskas-Warren <sauski@google.com>
Commit-Queue: Theodore Olsauskas-Warren <sauski@google.com>
Cr-Commit-Position: refs/heads/main@{#1088666}