Notify user when forced to boot into safe mode

When the device is forced into safe mode due to a security
compromise (persist.sys.audit_safemode has been set), notify
the user and provide access to a help article.

Bug: 27308928
Bug: 26902605
Change-Id: Ief7451f2d741eb888e5b111061aab5dc29525ea5
3 files changed