Implement Reverse String Function in Java

[ABHIRANJAN-KUMAR1]

📘 Implement Reverse String Function in Java (User Input + Example)

✔ Overview
This Pull Request adds a new Java program named ReverseString.java inside the Java directory.
The program takes user input, reverses the string, and prints the reversed result.
It includes clean comments, example usage, and follows beginner-friendly coding style.

🔧 Features

• Takes input from the user
• Reverses a string using StringBuilder
• Provides example inside comments
• Clean, readable, and well-structured code
• Good addition for beginners learning Java
• Hacktoberfest-friendly contribution

📂 File Added
Java/ReverseString.java

▶ Example Output
Enter a string to reverse: Sudipta
Reversed String: atpiduS

🎉 Why This Is Helpful

• Adds a useful basic Java program to the repository
• Demonstrates string manipulation clearly
• Helps new contributors
• Supports Hacktoberfest participation

🔗 Issue
Closes #2860

🚀 Ready for Review
Please review and merge this PR. Thank you! 🙌