Add new website metric reporting user policies and map to pref

This change adds new website metric reporting policies that control
website activity and usage telemetry reporting. This also maps these new
policies with respective prefs so metric reporting components can easily
look them up and subscribe to changes as needed.

Bug: b:237811626
DD: go/i&i_website_usage
Change-Id: I1105cc8d34b8cedd28e6a4a76527b25a3c4128e1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4735840
Reviewed-by: Maksim Ivanov <emaxx@chromium.org>
Reviewed-by: Hong Xu <xuhong@google.com>
Reviewed-by: Scott Violet <sky@chromium.org>
Reviewed-by: Leonid Baraz <lbaraz@chromium.org>
Reviewed-by: Fabio Tirelo <ftirelo@chromium.org>
Commit-Queue: Vignesh Shenvi <vshenvi@google.com>
Cr-Commit-Position: refs/heads/main@{#1180469}