RetinaNetPostProcess

This is the RetinaNetPostProcess model postprocessing class, which is inherited from the object detection post-processing base class (ObjectPostProcessBase).

The Init(), DeInit(), and Process() APIs in ObjectPostProcessBase are reloaded. For details, see ObjectPostProcessBase. It also reloads the assignment operator "=".

In addition, it implements the std::shared_ptr<MxBase::RetinaNetPostProcess> GetObjectInstance() method to obtain the smart pointer instance of this class.