Add Hopcroft-Karp algorithm and doctests for manual_accuracy function

[G26karthik]

Contributes to #9943

Description

This PR includes two contributions:

1. Hopcroft-Karp Algorithm Implementation: Adds the Hopcroft-Karp algorithm for finding maximum matching in bipartite graphs, a fundamental graph algorithm with O(E√V) time complexity.

2. Test Coverage Improvement: Adds comprehensive doctests to the manual_accuracy() function in machine_learning/scoring_functions.py.

Changes

New Algorithm

• Added graphs/hopcroft_karp.py with full implementation
• Includes detailed docstring and usage examples
• Comprehensive doctests covering various graph scenarios

Enhanced Test Coverage

• Added docstring with detailed function description for manual_accuracy()
• Added 4 doctest examples covering:
  • High accuracy (80% correct predictions)
  • Perfect accuracy (100% correct)
  • Zero accuracy (completely wrong predictions)
  • Complete inverse predictions (0% accuracy)

Testing

• All doctests pass successfully for both contributions
• Hopcroft-Karp: Multiple test cases for bipartite matching
• manual_accuracy: 12 doctest lines (4 examples) all passing
• Existing tests for mae, mse, rmse, rmsle, mbd remain passing

[Tarannum9623]

Hi! Can you help me by telling why my build test is failing, I want to contribute search_in_a_rotated_sorted_array in search directory and my build test failed. PR: Search in rotated sorted array #13245