recorder: allow to continue recording after a switch input

src/media/audio/audio_input.cpp

src/media/audio/audio_input.h

src/media/audio/audio_receive_thread.cpp

src/media/audio/audio_receive_thread.h

src/media/audio/audio_rtp_session.cpp

src/media/rtp_session.h

src/media/video/video_input.cpp

src/media/video/video_input.h

src/media/video/video_receive_thread.cpp

src/media/video/video_receive_thread.h

src/media/video/video_rtp_session.cpp

src/sip/sipcall.cpp

src/sip/sipcall.h