Make the AuthSchemes policy support dynamic refresh

This is in preparation for the new policy that allows some domains to
use any http authentication scheme regardless of the AuthSchemes  policy

Bug: 549273,1198536
Change-Id: Icc904b884f847f9c0cee777fbe14550c92af2196
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3370428
Reviewed-by: Matt Menke <mmenke@chromium.org>
Reviewed-by: Rohit Rao <rohitrao@chromium.org>
Reviewed-by: Owen Min <zmin@chromium.org>
Reviewed-by: Nasko Oskov <nasko@chromium.org>
Reviewed-by: Nate Fischer <ntfschr@chromium.org>
Reviewed-by: Alex Ilin <alexilin@chromium.org>
Commit-Queue: Yann Dago <ydago@chromium.org>
Cr-Commit-Position: refs/heads/main@{#961187}