feat(graph): add A* search algorithm implementation in Java

[shashu8660]

Summary

Added a self-contained implementation of the A* (A-Star) path-finding algorithm in Java.

Changes

• New file: AStar.java
• Implements generic A* search with a Heuristic interface and demo main method.
• Demonstrates Dijkstra behaviour when heuristic = 0.

Why

Adds a core path-finding algorithm to the algorithms repository.

Testing

javac AStar.java
java AStar
# Expected output: Shortest path: [A, B, C]

[IamBisrutPyne]

Hey @shashu8660

This is an outstanding submission.
To ensure mergeability, please remove the Binary files as they do not uphold the Repository standards.
Also, please add a metadata header to AStar.java owing to the repository conventions.

Thank you for your excellent contribution! 🌟

[shashu8660]

Thank you for your assist @IamBisrutPyne really thank for pointing the mistake as of this my first pull request it help me to learn a lot. And as per the request I have updated the pull request plz go through it and check if any more changes need to be made