non-mainline telephony related AIDL refactor/decoupling

1. decouple IOnSubscriptionChangedListener AIDL from telephonyMainline

2. other refactor. moving APIs which will not be included in
telephony mainline to frameworks/base/core/java/android/telephony.
Moving internal classes like AIDL which will not be included in
telephony mainline to
framework/base/core/java/com/android/internal/telephony

3. remove subscriptionMonitor which can be easily replaced with
SubscriptionManager.addOnSubscriptionChangedListener API

Bug: 140908357
Test: Build & unit test
Change-Id: I89c77ae7f006437e954af0d42491217a9f24b64d