[ENH] basic "test all estimators" suite

[fkiraly]

Adds a TestAllEstimators which checks generic fit/predict capabilities of estimators.

This is partly migrated from sktime, and uses the scikit-base test framework classes (also originally from sktime).

This can also be used as a joint refactor point with sktime and skbase.

Additions and changes:

• TestAllEstimators class
• this requires a BaseFixtureGenerator which generates scenarios. For this, the skpro fixture generator now inherits from skbase.
• Also, scenarios are required. This is not available in skbase yet, so the sktime scenario framework is copied to tests.scenarios.
• In incremental testing, an override is introduced so all classes are tested if the central test framework module changes.

[codecov-commenter]

Codecov Report

Attention: 77 lines in your changes are missing coverage. Please review.

Comparison is base (4d05959) 71.67% compared to head (6129c9a) 71.63%.
Report is 1 commits behind head on main.

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Additional details and impacted files

@@            Coverage Diff             @@
##             main      #89      +/-   ##
==========================================
- Coverage   71.67%   71.63%   -0.05%     
==========================================
  Files          93       97       +4     
  Lines        4950     5157     +207     
  Branches      900      952      +52     
==========================================
+ Hits         3548     3694     +146     
- Misses       1173     1206      +33     
- Partials      229      257      +28     

Files	Coverage Δ
skpro/utils/random_state.py	100.00% <100.00%> (ø)
skpro/tests/scenarios/scenarios_regressor_proba.py	79.48% <79.48%> (ø)
skpro/tests/test_all_estimators.py	88.33% <83.63%> (+4.27%)	⬆️
skpro/tests/scenarios/scenarios_getter.py	47.36% <47.36%> (ø)
skpro/tests/scenarios/scenarios.py	42.02% <42.02%> (ø)

... and 2 files with indirect coverage changes

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