We do this by manually managing the RTCAudioSession.
Unfortunately to do this we have to include a couple of RTC headers not
exported by the default build of WebRTC.framework (see: Libraries/WebRTC)
// FREEBIE
This makes sense as PeerConnectionClient is our interface to WebRTC
- Makes it easier to test PeerConnectionClient and CallService
- Allows us to shrink CallService class a bit (it's huge)
// FREEBIE
* Ensure NotificationsManager has dependencies
Otherwise it's easy to mess up the order of the required dependencies.
* move AccountManager into Environment, it's heavy to construct
// FREEBIE