Removed universal reference overload which are useless and cause issue when stealing the pointer for Python

- Change Softmax_Op 'axis' attributes from int to size_t
- Change Transpose_OpImpl to TransposeImpl
- Change snake-case to camel-case names
- fix tests according to AvgPooling_Op changes

- Move code definition in an external cpp file in src directory
- Remove InChannels, OutChannels, NbChannels from the list of attributes as they are only used for creating the associated Producer. They are kept as parameters of the Operator factory function to continue creating Weight and Bias Producers automatically. The number of in/out channels is now based on the Weight parameter
- 'Conv_Op::inChannels()', 'Conv_Op::outChannels()', 'ConvDepthWise::nbChannels()' functons added

- Change Softmax_Op 'axis' attributes from int to size_t
- Change Transpose_OpImpl to TransposeImpl
- Change snake-case to camel-case names
- fix tests according to AvgPooling_Op changes

- Move code definition in an external cpp file in src directory
- Remove InChannels, OutChannels, NbChannels from the list of attributes as they are only used for creating the associated Producer. They are kept as parameters of the Operator factory function to continue creating Weight and Bias Producers automatically. The number of in/out channels is now based on the Weight parameter
- 'Conv_Op::inChannels()', 'Conv_Op::outChannels()', 'ConvDepthWise::nbChannels()' functons added