gfe-relnote: (n/a) Pluming work for loss detection tuning using go/smartchoices. No behavior change, not protected. This adds 4 'broadcast' points to a quic session: SetLossDetectionTuner, OnMinRttAvailable, OnConfigNegotiated and OnConnectionClosed. Currently nothing is done at these points. The next CL will implement a loss detection tuner and use it from uStreamer. PiperOrigin-RevId: 298729689 Change-Id: I90cabde07e9d4a1ab82b66cd4d416005db5ee7ec