Draft: Add first version of run_notebook_pipeline

This MR adds a run_notebook_pipeline in order to automatically create a multicard page for https://git.opencarp.org/openCARP/onboarding (like we have for the examples: https://opencarp.org/documentation/examples).

• I like the .pipeline folder in https://git.opencarp.org/openCARP/experiments/ so I suggest that each tutorial folder gets one, which includes a metadata.yaml and at least one image. Alternatively we could parse the metadata from the notebook and put all the images in a images folder in the root of this repo (like we do for https://git.opencarp.org/openCARP/experiments/). We could also call the folder meta to match the help folder.

• I think it is good if we actually add a page in GRAV for each notebook, then the creation of the multicard page is the same as for the examples. Initially we discussed that there should be only a link on the card that leads to https://git.opencarp.org/openCARP/onboarding or a running version of jupyter (or now to binder?). In this case we could leave the page for each notebook empty. We could, however, show a rendered version of the notebook on the page with some links how and where to run it. The rendered notebook would look a bit like here https://git.opencarp.org/openCARP/onboarding/-/blob/main/Tutorials/single_cell/01_basic_bench/tutorial.ipynb?ref_type=heads.

Adding @gunnar.seemann and @m.houillon .