Add enterprise policy to disable feature NewBaseUrlInheritanceBehavior.

This CL adds an enterprise policy that can be used as a kill-switch
while the new base url inheritance behavior is rolled out.

Bug: 1356658
Change-Id: Iff1acd47bf1a47384924cf66e514368ff6315491
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4067503
Reviewed-by: Charlie Reis <creis@chromium.org>
Reviewed-by: Avi Drissman <avi@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: James Maclean <wjmaclean@chromium.org>
Reviewed-by: Julian Pastarmov <pastarmovj@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1079428}