[Favicons] Add page_url_type to AddIconMapping

This CL adds `page_url_type` as a parameter to the method
`AddIconMapping` and propagates the new argument upstream to the point
at which it is possible to differentiate redirects from regular
navigations so the correct `page_url_type` can be set. `page_url_type`
is also added as a member variable to `IconMapping` and is set correctly
from methods querying for a vector of `IconMapping` objects. This is
used to correctly overwrite the `page_url_type` if that is the only
property of the mapping that changes.

The reasoning for this change is that a new page_url_type column has
been added to the icon_mapping. The new column will be used in a
follow-up CL to change the behavior of `FindFirstPageURLForHost` to
prioritize kRegular entries over kRedirect entries as typically falling
back to the primary favicon for a host from kRegular navigations is
preferable to getting a favicon for a redirect that is possibly
cross-host.

Bug: 40881507
Change-Id: Ie632ad2b9f19b6b3309cf57b865f15996fa870ef
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6219282
Reviewed-by: Marc Treib <treib@chromium.org>
Commit-Queue: Calder Kitagawa <ckitagawa@chromium.org>
Reviewed-by: Peter Kotwicz <pkotwicz@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1419945}