Allowlist new extension for networkingPrivate and enterprise.platformKeys

The networkingPrivate API is deprecated, however, the getCertificateLists() method is missing in networking.onc, so networkingPrivate is still required here.
A long-term plan is being worked on to remove the dependency on networkingPrivate.

Bug: 1483151

Change-Id: I9331d999153017e0684147e59eed6a17b799ae83
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4865917
Reviewed-by: Pavol Marko <pmarko@chromium.org>
Auto-Submit: Yufeng Cheng <yfcheng@google.com>
Reviewed-by: Devlin Cronin <rdevlin.cronin@chromium.org>
Commit-Queue: Yufeng Cheng <yfcheng@google.com>
Cr-Commit-Position: refs/heads/main@{#1204994}