Add LightGBM Regressor and Classifier test function

[ZohaibHassan16]

Description

This PR introduces LightGBM-based test functions, which includes both a Regressor and a Classifier.

Related Issues

Fixes #6

Type of Change

• [ X] [ENH] - New feature (non-breaking change adding functionality)

How was this solved?

Here is what I did:

1. Created the Classes: Built LightGBMRegressorFunction and LightGBMClassifierFunction classes.
2. Hyperparameters & Stuff: Set up a search space with 9 params, used a closure in objective func and made sure model works with library's surrogate system.
3. Registered Everything: I updated the __init__.py files in both folders

Checklist

Required

• [ x] PR title includes appropriate tag: [ENH]
• [ x] Code passes make check (lint, format, isort)

Tests

• [ x] No tests needed (briefly explain why: The implementation follows established, verified temps by using existing models like RandomForest and DecisionTree, I just adhered to their convention)

Documentation

• [ x] Documentation added/updated (docstrings, user guide, examples)

Note: New features ([ENH]) typically require both tests and documentation.
Bug fixes ([BUG]) should include a regression test when possible.

Testing

Verification can be performed by instantiating the classes and checking the search space or objective function:
from surfaces.test_functions.machine_learning.hyperparameter_optimization.tabular.regression import LightGBMRegressorFunction lgbm_f = LightGBMRegressorFunction(dataset="diabetes", cv=5) print(lgbm_f.search_space) lgbm_f._create_objective_function() print(f"Pure objective function ready: {lgbm_f.pure_objective_function is not None}")

[SimonBlanke]

Thanks for opening the PR. I'll look into this. In the meantime you should also add this new feature to the docs: https://github.com/SimonBlanke/Surfaces/tree/main/docs/source

[ZohaibHassan16]

Hey @SimonBlanke , just did and also fixed a few module export issues which I stubbed into while testing docs in terminal. Let me know if you need anything else.