QGIS Descriptor CMake option

It would be convenient to add a high level CMake option in the OTB project to control whether QGIS descriptors should be built or not. It is currently possible to deactivate the build of the descriptors with the option -DOTB_OTB_BUILD_DEFAULT_MODULES=OFF and by deactivating the QGIS module with -DModule_OTBQGIS=OFF, but all other module should then be reactivated.

A OTB_WRAP_QGIS option could be added, ON by default, and would behave like OTB_WRAP_PYTHON