Restructure CarrierMessagingServiceWrapper with better interfaces.

- CarrierMessagingServiceWrapper is now a final class with only
APIs of direct actions on messaging.
- The original abstract parts of the class are now interfaces:
interface CarrierMessagingServiceConnectionCallback
and Runnable callback.
- CarrierMessagingCallbackWrapper is renamed to
CarrierMessagingCallback

Bug: 172087216
Test: build and manual
Change-Id: I1760623543b929a51ce26dc7dcc5f8ebe7fd9732