[ENH] interface MapieRegressor from mapie

[fkiraly]

Fixes #134.

Interfaces mapie.regression.MapieRegressor, and introduces mapie as an optional soft dependency.

Proof-of-concept for third party package interfaces, similar to sktime third party interface handling

Depends on:

• [ENH] integrate check_estimator with TestAllEstimators and TestAllRegressors for python command line estimator testing #138 for manual testing
• [ENH] improved conditional testing #140 for CI testing
• [BUG] fix test fixture generation logic #142 for CI testing (bugfix)

[fkiraly]

Failures in run-tests-no-extras are benign, due to test framework not excluding estimators which require extras. This can be solved by copying the same logic from sktime (should probably be in skbase at some point).

[codecov-commenter]

Codecov Report

Attention: 24 lines in your changes are missing coverage. Please review.

Comparison is base (a560ec7) 71.92% compared to head (a11f6d1) 63.86%.
Report is 1 commits behind head on main.

❗ Your organization needs to install the Codecov GitHub app to enable full functionality.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #136      +/-   ##
==========================================
- Coverage   71.92%   63.86%   -8.07%     
==========================================
  Files          98      100       +2     
  Lines        5290     5369      +79     
  Branches      978      990      +12     
==========================================
- Hits         3805     3429     -376     
- Misses       1214     1668     +454     
- Partials      271      272       +1     

Files	Coverage Δ
skpro/distributions/tests/test_all_distrs.py	27.46% <100.00%> (-65.50%)	⬇️
skpro/regression/tests/test_all_regressors.py	100.00% <100.00%> (ø)
skpro/tests/test_all_estimators.py	85.00% <100.00%> (+0.70%)	⬆️
skpro/utils/validation/_dependencies.py	37.50% <0.00%> (+6.73%)	⬆️
skpro/tests/test_switch.py	70.83% <70.83%> (ø)
skpro/regression/mapie.py	73.58% <73.58%> (ø)

... and 14 files with indirect coverage changes

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.