ENH: query confidence index capability

...rning/Supervised/include/otbBoostMachineLearningModel.txx

...upervised/include/otbDecisionTreeMachineLearningModel.txx

...ed/include/otbGradientBoostedTreeMachineLearningModel.txx

...ised/include/otbKNearestNeighborsMachineLearningModel.txx

...ning/Supervised/include/otbLibSVMMachineLearningModel.txx

...les/Learning/Supervised/include/otbMachineLearningModel.h

...pervised/include/otbNeuralNetworkMachineLearningModel.txx

...Supervised/include/otbNormalBayesMachineLearningModel.txx

...pervised/include/otbRandomForestsMachineLearningModel.txx

...earning/Supervised/include/otbSVMMachineLearningModel.txx