Added AO* algorithm

[Mastermind-sap]

Describe your change:

This pull request introduces a new implementation of the AO* (And-Or Star) search algorithm for solving AND-OR graphs in the machine_learning/ao_star.py file. The AO* algorithm is useful for problems where nodes can represent both OR decisions and AND decompositions, generalizing standard search trees. The implementation includes documentation, type hints, and several usage examples, making it easy to understand and use.

New AO* Algorithm Implementation

• Added a complete, well-documented implementation of the AO* (And-Or Star) search algorithm in machine_learning/ao_star.py, including helper functions for node updates and recursive solving.
• Provided detailed docstrings and example usages for the main ao_star function, demonstrating how to construct AND-OR graphs and apply the algorithm.
• Included a demo graph and heuristics in the __main__ block, allowing users to run and observe the algorithm's output directly.

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• [x] Add an algorithm?
• [ ] Fix a bug or typo in an existing algorithm?
• [ ] Add or change doctests? -- Note: Please avoid changing both code and tests in a single pull request.
• [ ] Documentation change?

Checklist:

• [x] I have read CONTRIBUTING.md.
• [x] This pull request is all my own work -- I have not plagiarized.
• [x] I know that pull requests will not be merged if they fail the automated tests.
• [x] This PR only changes one algorithm file. To ease review, please open separate PRs for separate algorithms.
• [x] All new Python files are placed inside an existing directory.
• [x] All filenames are in all lowercase characters with no spaces or dashes.
• [x] All functions and variable names follow Python naming conventions.
• [x] All function parameters and return values are annotated with Python type hints.
• [x] All functions have doctests that pass the automated testing.
• [x] All new algorithms include at least one URL that points to Wikipedia or another similar explanation.
• [x] If this pull request resolves one or more open issues then the description above includes the issue number(s) with a closing keyword: "Fixes #ISSUE-NUMBER".