Add CMake flag to disable QGIS descriptors
See: https://forum.orfeo-toolbox.org/t/otb-without-qgis/281
default value should be ON
related to #1910 (closed)
See: https://forum.orfeo-toolbox.org/t/otb-without-qgis/281
default value should be ON
related to #1910 (closed)