REFAC: make std::string overload the main implementation

...rs/GdalAdapters/include/otbOGRExtendedFilenameToOptions.h

...ters/GdalAdapters/src/otbOGRExtendedFilenameToOptions.cxx

Modules/Core/Common/include/otbExtendedFilenameHelper.h

Modules/Core/Common/src/otbExtendedFilenameHelper.cxx

...ndedFilename/include/otbExtendedFilenameToReaderOptions.h

...ndedFilename/include/otbExtendedFilenameToWriterOptions.h

...tendedFilename/src/otbExtendedFilenameToReaderOptions.cxx

...tendedFilename/src/otbExtendedFilenameToWriterOptions.cxx

Modules/IO/ImageIO/include/otbImageFileReader.h

Modules/IO/ImageIO/include/otbImageFileReader.hxx

Modules/IO/ImageIO/include/otbImageFileWriter.h

Modules/IO/ImageIO/include/otbImageFileWriter.hxx

...s/MPI/MPITiffWriter/include/otbSimpleParallelTiffWriter.h

...MPI/MPITiffWriter/include/otbSimpleParallelTiffWriter.hxx

Modules/MPI/MPIVrtWriter/include/otbMPIVrtWriter.h

Modules/MPI/MPIVrtWriter/include/otbMPIVrtWriter.hxx