Merge "Add 2 APIs in ExtendedTimeZoneNames and ExtendedTimeZone" am: 1cb623da40

Original change: https://android-review.googlesource.com/c/platform/external/icu/+/1541849

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: Id15f9d36a8b51599f356d22ff26353cf32c79896