Add median of two sorted arrays implementation #13717

[anshmittal2004]

Closes #13717

Added O(log(min(m,n))) implementation for median of two sorted arrays in divide_and_conquer/.

• Uses binary search on partitions.
• Includes docstring with examples and complexity.
• Handles edge cases (empty arrays, odd/even lengths).
• Added basic test cases.

[Hacktoberfest 2025 contribution]

[algorithms-keeper]

Closing this pull request as invalid

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