Merge branch 'optional_shark_dimensionality_reduction' into 'develop'

CMake/OTBModuleHeaderTest.cmake

...ionalityReduction/app/otbTrainDimensionalityReduction.cxx

...plications/AppDimensionalityReduction/test/CMakeLists.txt

...arning/include/otbDimensionalityReductionModelFactory.hxx

...Learning/DimensionalityReductionLearning/otb-module.cmake

...rning/DimensionalityReductionLearning/test/CMakeLists.txt

...ing/test/otbDimensionalityReductionLearningTestDriver.cxx

...ng/DimensionalityReductionLearning/test/tests-shark.cmake

Modules/Learning/Unsupervised/CMakeLists.txt

Modules/Learning/Unsupervised/otb-module.cmake

Modules/Learning/Unsupervised/test/CMakeLists.txt

Modules/Learning/Unsupervised/test/tests-shark.cmake