Handle plated vs non-plated copper for copper other than pads.

3d-viewer/3d_canvas/board_adapter.cpp

3d-viewer/3d_canvas/board_adapter.h

3d-viewer/3d_canvas/create_layer_items.cpp

3d-viewer/3d_rendering/opengl/create_scene.cpp

3d-viewer/3d_rendering/opengl/render_3d_opengl.cpp

3d-viewer/3d_rendering/raytracing/create_scene.cpp

3d-viewer/3d_viewer/eda_3d_viewer_settings.cpp

3d-viewer/3d_viewer/eda_3d_viewer_settings.h

3d-viewer/dialogs/panel_3D_display_options.cpp