ENH: Add serialization for incremental linear models

[olegkkruglov]

Description

• Added __getstate__ method to IncrementalLinearRegression and IncrementalRidge
• Removed redundant check for onedal table backend in onedal/datatypes/data_conversion.cpp. It is necessary because partial result for linear models contains column-major tables on C++ side. Serialization tests confirm conversion actually works well for column-major tables as well.
• Finalization is called with serialization during __getstate__ method
• _need_to_finalize flag is added to avoid unnecessary call of finalization backend.
• Added test for checking if it works well
• Updated deselected_tests.yaml

---

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Checklist to comply with before moving PR from draft:

PR completeness and readability

• I have reviewed my changes thoroughly before submitting this pull request.
• I have commented my code, particularly in hard-to-understand areas.
• I have updated the documentation to reflect the changes or created a separate PR with update and provided its number in the description, if necessary.
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• I have run it locally and tested the changes extensively.
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• I have extended testing suite if new functionality was introduced in this PR.

Performance

• I have measured performance for affected algorithms using scikit-learn_bench and provided at least summary table with measured data, if performance change is expected.
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• I have extended benchmarking suite and provided corresponding scikit-learn_bench PR if new measurable functionality was introduced in this PR.

[icfaust]

/intelci: run

[david-cortes-intel]

Since this note will appear in multiple classes, perhaps it could be moved into a common variable and the docstrings modified programmatically for all the classes that will have the note.

[olegkkruglov]

It is good idea. I think it could be done in a separate PR moving some common things for all incremental algorithms to separate classes/variables.

[icfaust]

/intelci: run

[codecov]

Codecov Report

Attention: Patch coverage is 72.58065% with 17 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
onedal/linear_model/linear_model.cpp	35.29%	2 Missing and 9 partials ⚠️
...edal/spmd/linear_model/incremental_linear_model.py	0.00%	3 Missing ⚠️
onedal/linear_model/incremental_linear_model.py	95.00%	1 Missing and 1 partial ⚠️
onedal/datatypes/data_conversion.cpp	50.00%	0 Missing and 1 partial ⚠️

Flag	Coverage Δ
azure	78.04% <88.37%> (+0.02%)	⬆️
github	71.06% <76.27%> (+0.01%)	⬆️

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

Files with missing lines	Coverage Δ
sklearnex/linear_model/incremental_linear.py	81.56% <ø> (ø)
sklearnex/linear_model/incremental_ridge.py	83.21% <ø> (ø)
onedal/datatypes/data_conversion.cpp	50.00% <50.00%> (+0.23%)	⬆️
onedal/linear_model/incremental_linear_model.py	97.75% <95.00%> (+0.60%)	⬆️
...edal/spmd/linear_model/incremental_linear_model.py	35.71% <0.00%> (-4.29%)	⬇️
onedal/linear_model/linear_model.cpp	55.88% <35.29%> (-1.91%)	⬇️

[icfaust]

/intelci: run