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.
Change-Id: I668bc8ac0cb78f3d4d9a4b7ad6ac1534b88af833