Integrate vtk9

Integrate the VTK 9 patches and generate a suitable docker container to test.

TODO:

• upload container to registry
• add gitlab-ci entry to run it

.gitlab-ci.yml

@@ -320,7 +320,7 @@ build-openmpi-complete-gcc10:
 build-openmpi-complete-gcc10-vtk9:
     stage: build_openmpi_gcc10_vtk9
     image:
-        name: registry.jsc.fz-juelich.de/slms/loadbalancing/openmpi-gcc10-full-vtk9:latest
+        name: registry.jsc.fz-juelich.de/slms/loadbalancing/vtk9-v1:latest
         entrypoint: ["/bin/bash", "--rcfile", "/etc/profile", "-l", "-c"]
     tags:
         - public-docker