libbrillo: Add new policy (DeviceUpdateStagingSchedule) for staging updates.

Add a new device policy that will allow administrators to specify a schedule
for rolling out updates to an organizational unit.

TEST=Used YAPS as DM server, verified that the new policy is parsed correctly.

Change-Id: I72852ddf86e6c7e432aea38a33c6fb3be4c7f315
Commit-Ready: ChromeOS CL Exonerator Bot <>
Tested-by: May Lippert <>
Reviewed-by: Dan Erat <>
5 files changed