[ #60972 ] Move Video classes to a new namespace

src/CMakeLists.txt

src/account.cpp

src/account.h

src/audio/codecmodel.cpp

src/call.cpp

src/call.h

src/phonenumber.cpp

src/phonenumber.h

src/private/videochannel_p.h

src/private/videocodec_p.h

src/private/videodevice_p.h

src/uri.cpp

src/uri.h

src/video/channel.cpp

src/video/channel.h

src/video/codec.cpp

src/video/codec.h

src/video/codecmodel2.cpp

src/video/codecmodel2.h

src/video/device.cpp