[AutoReload] Add policy definition for idp login auto reload feature

Design doc: go/auto-reload-3pidp

Bug: b/330476464
Change-Id: I90eb61a0f346195e7dfc27498b4e2adb6812ee5b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5380090


Reviewed-by: Denis Kuznetsov <antrim@chromium.org>
Reviewed-by: Owen Min <zmin@chromium.org>
Commit-Queue: Aya Elgendy‎ <ayag@chromium.org>
Reviewed-by: Andrey Davydov <andreydav@google.com>
Cr-Commit-Position: refs/heads/main@{#1282189}