Add Maximum Subarray Sum Algorithm

[yuvraj-rathod-1202]

I would like to implement the Maximum Subarray Sum algorithm using Kadane's Algorithm in the "pydatastructs/linear_data_structures/algorithms.py" file. This algorithm finds the contiguous subarray with the largest sum in an array, solving the problem in O(n) time complexity.

i will do below things:

1. Implementation in pydatastructs/linear_data_structures/algorithms.py.
2. Add unit tests to validate the implementation.
3. Ensure proper documentation and examples in the function docs.
4. Run existing test cases to ensure no conflicts.

This is my first contribution to the project as part of my journey toward Google Summer of Code 2025. I'm excited to learn and contribute to this repository. Feedback and suggestions are highly appreciated!

Can i go ahead?

[yuvraj-rathod-1202]

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