JVET-AE0050 item 1: Add nnpfa_no_prev_clvs_flag to the NNPFA SEI message

doc/software-manual.tex

source/App/DecoderApp/DecApp.cpp

source/App/EncoderApp/EncApp.cpp

source/App/EncoderApp/EncAppCfg.cpp

source/App/EncoderApp/EncAppCfg.h

source/Lib/CommonLib/Picture.cpp

source/Lib/CommonLib/Picture.h

source/Lib/CommonLib/SEI.cpp

source/Lib/CommonLib/SEI.h

source/Lib/CommonLib/SEINeuralNetworkPostFiltering.cpp

source/Lib/CommonLib/SEINeuralNetworkPostFiltering.h

source/Lib/CommonLib/TypeDef.h

source/Lib/DecoderLib/DecLib.h

source/Lib/DecoderLib/SEIread.cpp

source/Lib/EncoderLib/EncCfg.h

source/Lib/EncoderLib/SEIEncoder.cpp

source/Lib/EncoderLib/SEIwrite.cpp