Prepare for rate limiting TimeZoneProviderService

Prepare for rate limiting TimeZoneProviderService.  The first step is to
add duplicate event detection. Later, this will be extended to add a
time component.

i.e. the android.service.timezone.TimeZoneProviderService
will pass on suggestions that are semantically different from a previous
event, but will not if they are semantically the same.

In a later commit it will be made to pass on changes that are the same but
newer than some threshold.

Most of the changes in this commit are to track a change to the binder
API and the move of TimeZoneProviderEvent so that it can be used in code
outside of the system server.

Also:
+ TimeZoneProviderService is now stateful, so add dump() implementation.
Because dump() is called on the main thread, add locks needed for safe
threading (previously, all logic took place on a known handler thread).

Test: atest hostsidetests/time/host/src/android/time/cts/host/LocationTimeZoneManagerHostTest.java
Test: atest core/tests/coretests/src/android/service/timezone/TimeZoneProviderEventTest.java
Test: atest services/tests/servicestests/src/com/android/server/timezonedetector/location/ZoneInfoDbTimeZoneProviderEventPreProcessorTest.java
Test: treehugger
Bug: 197624972
Bug: 200710190
Change-Id: Ia3246e969fda61836c8e1eee3007a8177d119994