REFAC: replace IsAlphaNum() by a lambda

...tions/AppClassification/app/otbComputeConfusionMatrix.cxx

...tions/AppClassification/app/otbPolygonClassStatistics.cxx

...pplications/AppClassification/app/otbSampleExtraction.cxx

...Applications/AppClassification/app/otbSampleSelection.cxx

...plications/AppClassification/include/otbTrainVectorBase.h

...ications/AppClassification/include/otbTrainVectorBase.hxx

...lications/AppClassification/include/otbVectorPrediction.h

...cations/AppClassification/include/otbVectorPrediction.hxx

...onalityReduction/app/otbVectorDimensionalityReduction.cxx