Add a time field to GeolocationTimeZoneSuggestion

Add a time field to GeolocationTimeZoneSuggestion for use in upcoming
fallback logic. This is should help establish ordering across
different time zone detection mechanisms.

Bug: 197624972
Test: treehugger
Test: frameworks/base: atest services/tests/servicestests/src/com/android/server/timezonedetector/
Test: cts: atest hostsidetests/time/host/
Change-Id: I824679f3eca39a69d5413d365889ad8566d3e557