init parallel trees method

[Alexandr-Solovev]

Description

Summary

This PR introduces a new method local_trees for the Random Forest implementation. The method builds local trees independently on each GPU node, enabling efficient parallelization and improved scaling.

Key Changes

• ✅ Added local_trees method for distributed tree construction across GPUS.
• ✅ Introduced functionality to copy local trained models in the global model.
• ✅ Added explicit calls for model serialization and deserialization(the distributed process based on the
  serialize local models -> allgather local models -> deserialize local models -> copy local models in the global model).

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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.
• Git commit message contains an appropriate signed-off-by string (see CONTRIBUTING.md for details).
• I have added a respective label(s) to PR if I have a permission for that.
• I have resolved any merge conflicts that might occur with the base branch.

Testing

• I have run it locally and tested the changes extensively.
• All CI jobs are green or I have provided justification why they aren't.
• 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.
• I have provided justification why performance has changed or why changes are not expected.
• I have provided justification why quality metrics have changed or why changes are not expected.
• I have extended benchmarking suite and provided corresponding scikit-learn_bench PR if new measurable functionality was introduced in this PR.

[Alexandr-Solovev]

/intelci: run

[Alexandr-Solovev]

/intelci: run

[Alexandr-Solovev]

/intelci: run

[Vika-F]

ABI checks looks as false positive, as adding virtual methods into a virtual class shouldn't be an issue. But maybe I am getting something wrong.

Please take a look at the other comments.

[ethanglaser]

/intelci: run

[Alexandr-Solovev]

/intelci: run

[Alexandr-Solovev]

/intelci: run

[Vika-F]

Let's wait for the CI and LGTM.