Add Qos Callback support

* Provide App Developers Qos related info associated to
  a bound socket through ConnectivityManager
* Qos sessions are generated and filtered by Network Agents
  and sent back through the Connectivity Service to the
  API consumer.
* The structure of the code within com.android.server
  is designed to support different types of filters in the
  the future.
* The first type of Qos Attributes are related to EPS
  Bearers in order support RCS.

Bug: 155176305
Test: Added to cts/NetworkAgentTest
Test: Added to ConnectivityServiceTest
Change-Id: I145dd065d9deeee449eb9695ab3f6c8556ee7c09