[Extensions] Determine whether to bypass redirect checks per request

This change introduces the BypassRedirectChecksPerRequest feature flag,
which is enabled by default. This flag allows redirect checks to be
bypassed only if the specific request was redirected by the extensions
layer.

Bug: 379337758
Change-Id: I995620efe045ca6eba6a02c3a64e91d18188af6b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6692491
Reviewed-by: Devlin Cronin <rdevlin.cronin@chromium.org>
Reviewed-by: Nasko Oskov <nasko@chromium.org>
Commit-Queue: Andrea Orru <andreaorru@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1485110}