Implemented the async recommendation request call.

Implemented requestAsyncRecommendation() by introducing a Handler
implementation to handle requests that time out and a OneTimeCallback
class to prevent multiple callbacks from being sent back for the same
request.

Change-Id: Ida2ff860d78d86185ab9ab22232b5b6dc1e4b310
Test: runtest frameworks-services -c com.android.server.NetworkScoreServiceTest
BUG:33784158