Unified plotting

As we are now collecting lots of contributions it turns out that plotting is very popular and I think this topic would be good fit for a first general functionality usable for lots of use cases.

I therefore propose to unify the current proposals into one which then can be easily pip-installed and used.

The following functionality should be included (incl. unique functionalities):

• @chleh: !1 (closed), plot along mesh axis
• @felikskiszkurno: !7 (merged), plot multiple sim runs, min/max over time
• @endJunction: https://gitlab.opengeosys.org/ufz-bgr/ebs/-/blob/main/plots.py, generic input (dataframes), generic plot styles, custom legends
• @bilke: https://gitlab.opengeosys.org/ufz-bgr/hpc/tutorial/-/blob/master/scripts/points.ipynb, xdmf input

I think these general point should be addressed too:

• Plot functions should only get the plot data as input (not a mesh or time series of meshes)
• Helper functions to prepare plot data from meshes and time series of meshes (VTU, PVD and XDMF / HDF5)
• Setup library structure (e.g. in lib-subdirectory) to build and publish to package registry
  • Implement testing
  • Documentation generation

If you generally agree you can directly edit this description to add TODOs or other points.