We plan to make ExternalTimeSuggestion part of a system API. This
CL moves it from android.app.timedetector to android.app.time in
preparation for this change.
Bug: 177079827
Test: atest services/tests/servicestests/src/com/android/server/timedetector/TimeDetectorStrategyImplTest.java
Test: atest android.app.timedetector
Test: atest android.app.time
Change-Id: I13f059afb10b57b13b0e340aacb924a43dabe172