remove opengl2 dependency from rendering core testing

Rendering/Core/Testing/Cxx/CMakeLists.txt

Rendering/Core/vtk.module

Rendering/OpenGL2/Testing/Cxx/CMakeLists.txt

Rendering/OpenGL2/Testing/Cxx/TestBlockOpacity.cxx

Rendering/OpenGL2/Testing/Cxx/TestBlockVisibility.cxx

...ng/OpenGL2/Testing/Cxx/TestCompositeDataPointGaussian.cxx

...2/Testing/Cxx/TestCompositeDataPointGaussianSelection.cxx

...ring/OpenGL2/Testing/Cxx/TestCompositePolyDataMapper2.cxx

...2/Testing/Cxx/TestCompositePolyDataMapper2CellScalars.cxx

.../TestCompositePolyDataMapper2MixedGeometryCellScalars.cxx

...ng/Cxx/TestCompositePolyDataMapper2MixedGeometryEdges.cxx

...enGL2/Testing/Cxx/TestCompositePolyDataMapper2Picking.cxx

...enGL2/Testing/Cxx/TestCompositePolyDataMapper2Scalars.cxx

...ting/Cxx/TestGlyph3DMapperTreeIndexingCompositeGlyphs.cxx

Rendering/OpenGL2/Testing/Cxx/TestHiddenLineRemovalPass.cxx

...enGL2/Testing/Cxx/TestMultiBlockPartialArrayFieldData.cxx

...enGL2/Testing/Cxx/TestMultiBlockPartialArrayPointData.cxx

Rendering/OpenGL2/Testing/Cxx/TestValuePassFloatingPoint.cxx

...OpenGL2/Testing/Data/Baseline/TestBlockOpacity.png.sha512

...enGL2/Testing/Data/Baseline/TestBlockOpacity_1.png.sha512