Add a listener for subscription changes to SimDialogFragment

For some kinds of telephony changes that might happen while we're
already showing one of these dialogs, we already get sent a new intent
for the dialog which we internally convert into a refresh of the dialog
contents instead of stacking a new copy on top of the old one.

But it turns out there are some other cases where the telephony stack
doesn't send a new intent for the dialog but *does* send a change event
through the SubscriptionManager, and we want to respond to those as
well. This CL adds a listener for those events.

Fixes: 135276696
Test: make RunSettingsRoboTests
Change-Id: Ifb93ae95f45fda5831e112306dd9361ccaa5119c