Harmonize model output directory kwarg

[dweindl]

Now it's all output_dir instead of model_output_dir or outdir.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 78.25%. Comparing base (8603c1e) to head (cdf4d4a).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3105   +/-   ##
=======================================
  Coverage   78.25%   78.25%           
=======================================
  Files         315      315           
  Lines       20464    20464           
  Branches     1500     1501    +1     
=======================================
  Hits        16014    16014           
  Misses       4441     4441           
  Partials        9        9           

Flag	Coverage Δ
cpp	71.74% <50.00%> (ø)
cpp_python	37.73% <33.33%> (ø)
petab	46.46% <100.00%> (ø)
petab_sciml	13.79% <16.66%> (ø)
python	70.37% <75.00%> (ø)
sbmlsuite-jax	32.90% <16.66%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
python/sdist/amici/exporters/sundials/de_export.py	96.38% <100.00%> (ø)
...hon/sdist/amici/importers/petab/_petab_importer.py	86.78% <100.00%> (ø)
...n/sdist/amici/importers/petab/v1/import_helpers.py	85.71% <100.00%> (ø)
...hon/sdist/amici/importers/petab/v1/petab_import.py	100.00% <ø> (ø)
...thon/sdist/amici/importers/petab/v1/pysb_import.py	61.76% <ø> (ø)
...thon/sdist/amici/importers/petab/v1/sbml_import.py	97.75% <ø> (ø)
python/sdist/amici/importers/pysb/__init__.py	94.64% <ø> (ø)
python/sdist/amici/importers/sbml/__init__.py	94.33% <ø> (ø)
python/sdist/amici/jax/ode_export.py	88.33% <100.00%> (ø)
...on/sdist/amici/sim/sundials/petab/v1/_simulator.py	96.66% <100.00%> (ø)
... and 4 more

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