Apply trivial subdomain stripping on url approval flows

Trivial subdomains are stripped from the url during the
execution of remote and local approval requests, via a
new formatter helper object.
Stripping as part of the
request leaves the url stored in the interstitial unchanged,
as this is publicly exposed and want to avoid modifying it.

The stripping the of the url is skipped conditionally
if and only if the existing full host entry is present in
the blocklist.

Bug: b/322484529
Change-Id: If173c762d93bdd381b593d78d941e2b21b9c7a01
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5268586


Auto-Submit: Anthi Orfanou <anthie@google.com>
Reviewed-by: Mustafa Emre Acer <meacer@chromium.org>
Reviewed-by: Nohemi Fernandez <fernandex@chromium.org>
Commit-Queue: Anthi Orfanou <anthie@google.com>
Cr-Commit-Position: refs/heads/main@{#1281949}