Implement UKM for CSPP

This CL adds four UKM metrics for client side phishing protection,
measuring the high-level behavior of the feature on a per-URL basis.
This will help to understand regressions that only appear on a subset
of pages.

Bug: 1320895
Change-Id: I62faa8b6767989c434b538641e7f7c8a4646d0bb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3636478
Reviewed-by: Robert Kaplow <rkaplow@chromium.org>
Commit-Queue: Daniel Rubery <drubery@chromium.org>
Reviewed-by: Xinghui Lu <xinghuilu@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1003878}