Tracking Protection: Add logic for fetching exceptions

The UI will be updated in an upcoming CL - this one is just for the
fetching logic.

Tested manually - render tests will be added once the UI is finished.
Low-Coverage-Reason: render tests not implemented yet.

Screenshot: https://screenshot.googleplex.com/BVjuNqjUxKJCLtu.png

Bug: b:295926938
Change-Id: Id3cf4687748c78db63096f68731747f5d5be01ed
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4896010
Reviewed-by: Bo Liu <boliu@chromium.org>
Reviewed-by: Theodore Olsauskas-Warren <sauski@google.com>
Commit-Queue: Andrey Zaytsev <andzaytsev@google.com>
Cr-Commit-Position: refs/heads/main@{#1202667}