Expose onEmergencyNumberListChanged, semantics change am: e182543791 am: f8e5b6fd6e am: 266e87e5a9

Original change: https://android-review.googlesource.com/c/platform/frameworks/base/+/1469715

Change-Id: I68d51c9e91f3a2c08a474f7848d4fda1693c21d9