[ci] Added ogs-serial-jupyter container image.

• Adds Jupyter notebook example (taken from ogs6py README).
• Adds a Docker container implementing a full Jupyter Lab environment with OGS and lots of Python tools.
• Runs the notebook example by CI.
• Freshly executed Notebook example is converted to and embedded into the website.

See docs preview.

See benchmark page created by notebook (images do not work here in preview)

Possible follow-ups:

• Implement notebook output checks (vktdiff? in Python? Fail the build if check did not pass).
• Refactor example notebook to use input file generators (Mesh, GML (@TomFischer)) and ogs6py to run a simulation completely without any pre-existing input files.

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• Closes #3193 (closed).
• Related to owf/ogs#1, owf/ogs#3 and owf/ogs#4.

1. Feature description was added to the changelog
2. Tests covering your feature were added?
3. Any new feature or behavior change was documented?