Apply new_usages_require_review to content

To keep consistent with the previous rule and to prevent developers
from randomly importing content layer into other layers we set requires
review on new dependencies.

Change-Id: I0b96a6d4dfd653f166a2479e6457b54320088b89
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5924517
Reviewed-by: Andrew Grieve <agrieve@chromium.org>
Reviewed-by: Alex Moshchuk <alexmos@chromium.org>
Commit-Queue: Dave Tapuska <dtapuska@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1367180}