Time zone update API classes

Time zone update API classes. Currently hidden but they
will go on to be unhidden in future.

This forms the basis of client and system server code to
support time zone updates.

Tests can be run with:

make -j30 FrameworksCoreTests
adb install out/target/product/angler/data/app/FrameworksCoreTests/FrameworksCoreTests.apk
adb shell am instrument -e package android.app.timezone \
    -w com.android.frameworks.coretests \
    "com.android.frameworks.coretests/android.support.test.runner.AndroidJUnitRunner"

Bug: 31008728
Test: See above.
Merged-In: I668bc8ac0cb78f3d4d9a4b7ad6ac1534b88af833
Change-Id: Icde574f8974152617a1f7ac9fa225bd5011dcce1