Add an interface media::ClientDeathObserver that abstracts away receiving key-based death notifications for clients associated to media::Player instances server-side
Provide an implementation media::HybrisClientDeathObserver that relies on hybris and ultimately on Android's onBinderDied to receive death notifications.
Adjust media::PlayerStub and media::PlayerImplementation to account for the new interface.
Adjust the CMake setup for tests to link media-hub-service instead of recompiling large parts of the implementation classes.
Approved by: Jim Hodapp, PS Jenkins bot