Implement RulesService::BlockScreenshots

Bug: 322519161
Change-Id: I0b2d0632a3dc43fa1ad4ded47d506d3d7c6570dc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5405353


Reviewed-by: Roger Tawa <rogerta@chromium.org>
Reviewed-by: Nasser Al-shawwa <alshawwa@chromium.org>
Commit-Queue: Dominique Fauteux-Chapleau <domfc@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1281293}