hooks: start enforcing basic filesystem sanity

To avoid people trying to create non-standard paths, add a hook to
reject any such attempts.

BUG=None
TEST=CQ passes

Change-Id: I787f9d274e27616e7643c300616aadf3258f7fed
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosutils/+/2065316
Tested-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Gwendal Grignou <gwendal@chromium.org>
2 files changed