Move suggestExternalTime to TimeManager

This CL moves suggestExternalTime method from TimeDetector to
TimeManager. Eventual goal is to make suggestExternalTime a System
API. Ideally all time related system APIs live in android.app.time
hence the move.

Test: atest android.app.time
Change-Id: I464545e77fdf68c35c8a338bfe5ac8b7535bc3e6
Bug: 177079827
7 files changed