Add suggestManualTimeZoneSuggestion to the client

Add TimeZoneDetector.suggestManualTimeZone() to set the time zone
"manually" and switch the device policy manager code over to using
it.

Add RequiredPermission annotations to TimeZoneDetector while there.

Bug: 140712361
Test: treehugger only
Test: atest services/tests/servicestests/src/com/android/server/devicepolicy/DevicePolicyManagerTest.java
Change-Id: Id247fddfdd793732dd88294ee215eda37cd0be4c