[DC] Normalize origin comparison in the low risk origin checker

This change updates the digital identity low risk origin checker to
 normalize origins before comparing them. In practice this means:

- Ignore `www.` when comparing hosts
- Match on schemes and ports.

The existing implementation was not tested. This CL also adds unit tests.

Bug: 418214604
Change-Id: I94218ca4b2524bde4e5c627cb696e9789a821848
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6563509
Reviewed-by: Adem Derinel <derinel@google.com>
Commit-Queue: Mohamed Amir Yosef <mamir@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1462241}