MSIM: Add support for DSDA.

1. Interface changes to inform local call hold and setActiveSubscription
to 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.

Change-Id: I942122eab45a19ea30abc92c90228d9115c1df78