Add support for DSDA.

1. Interface changes to inform local call hold and setActiveSubscription
telephony service from telecomm service.
2. Interface in Telecomm manager to query active subscription and switch
to other subscription.
3. Add support in PhoneAccount to maintain LCH & active subscription
information.
4. Interface changes to inform sub switch between inCallUI and Telecomm
service.

Conflicts:
telecomm/java/android/telecom/Call.java
telecomm/java/android/telecom/ParcelableCall.java
telecomm/java/android/telecom/Phone.java
telecomm/java/android/telecom/TelecomManager.java
telecomm/java/com/android/internal/telecom/IConnectionService.aidl
Change-Id: I942122eab45a19ea30abc92c90228d9115c1df78
Conflicts:
telecomm/java/com/android/internal/telecom/ITelecomService.aidl