OMS: Setup state for users on boot and when added

Some users never get switched to (managed profile/work profile) so the
overlay state for a user would never be setup (but they could still show
UI and apps).

This change ensures that user state is setup after an OTA to android O,
and whenever a user is added.

Bug: 37899201
Test: manual (add user via Device Admin sample: vendor/google/tools/DeviceAdminSample)
Change-Id: If214e26e39b18c2861794baf5c608a47d536e5ff