Rebase

This is marked as draft. I believe we are ready now to start merging,

• PR Remove deprecated functionality #308
• PR Remove deprecated parts of OMCPath #346
• PR Remove deprecated code in ModelicaSystem set*() functions #347
• PR Remove OMCSessionZMQ #387

But we should first update the users guide https://openmodelica.org/doc/OpenModelicaUsersGuide/latest/ompython.html

This is marked as draft. I believe we are ready now to start merging,
[...]
But we should first update the users guide https://openmodelica.org/doc/OpenModelicaUsersGuide/latest/ompython.html

I'm currently working on PR #404 - get Runner included / keep backward compatibility. The main points are:

• Define a runner functionality which allows to run compiled (binary) models without OMC (see PR Enable the usage of a pre-built model executables by ModelicaSystemRunner #401 / @joewa)
• Allow compatibility with OMPython 4.0.0 by defining a support layer on top of the latest code (see [OMCSession*] renames #384 (comment); @casella)

The code defined in the RFC #404 updates the internal structure of OMPython such that:

• generic code is separated in ABC classes
• derived code exists for OMC usage and Runner usage
• a compatibility layer exists such that the interface of OMPython 4.0.0 is (basically) supported

Furthermore, as OMCPath is working only for Python >= 3.12, another dimension exists. There is a dummy implementation of OMCPath for Python < 3.12 such that most of the functionality can also be used here. See PR #401 for a hint that even older Python version are used (Python 3.10 or even lower).

I did hold of documentation to finish work on this part; the new structure would be baseline of the documentation. My idea was to include the changes in 4.1.0 and create a cut at the next release (or keep some kind of compatibility layer alive).

To keep best compatibility, I did set the listed PR's as draft, i.e. to be included later.