Added: Tarjan's SCC algorithm and test cases

[vedas-dixit]

Pull Request Title:

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Description of the Change:

I’ve implemented Tarjan’s Algorithm for finding Strongly Connected Components (SCC) in a directed graph, and added test cases to ensure correctness. This algorithm uses a depth-first search (DFS) approach and provides an efficient solution for identifying SCCs.

What did I do?

• Implemented Tarjan's SCC algorithm.
• Created test cases for validating the algorithm's correctness.
• Ensured edge cases are covered in the test cases.

Checklist:

• [*] I have read the CONTRIBUTING.md guidelines.
• [*] This pull request is my own work and I have not plagiarized.
• [*] I understand that pull requests will not be merged if they fail the automated tests.
• [*] This PR only modifies the algorithm file related to Tarjan’s SCC.
• [*] All new files follow the UpperCamelCase naming convention (e.g., TarjanSCC.js).
• [*] I’ve linked any algorithm-related references or explanations in the comments.

Let me know if any adjustments are needed!