Add Josephus Problem solution in Java under java_programs

[SatyaLahariReddy]

• Implemented the Josephus Problem using a recursive approach.
• Added the solution in java_programs/JosephusProblem.java.
• The program calculates the safe position in a circle of n people, eliminating every k-th person until only one remains.
• Time Complexity: O(n), Space Complexity: O(n)

[SatyaLahariReddy]

Hi Maintainers 👋,

I have added a solution for the Josephus Problem in Java under the java_programs folder.
The program takes the total number of people (n) and step rate (k) as input and outputs the safe position using a recursive approach.

I would be grateful if you could review this PR and merge it.
Thank you! 🙏