Refactor SMS Middleware and SMS Send path.

Introduce a new Broadcast, ACTION_NEW_OUTGOING_SMS, that is similar to the existing call
equivalent ACTION_NEW_OUTGOING_CALL. This allows a receiver to rewrite the intent
or cancel it entirely.

This removes the need for injecting middleware.

Change-Id: I063288461161979f951932f32ade2cfbd72f8b73