Added BankManagement.java for Hacktoberfest

[IshikaBanga26]

Added BankManagement.java, a Java program that simulates a Bank Management System using Object-Oriented Programming concepts. The program includes a base Account class and two subclasses — SavingAccount and CurrentAccount — demonstrating inheritance and method overriding.

Users can perform operations like deposit, withdraw, display balance, and compute interest for savings accounts. The current account also checks for minimum balance and applies a penalty if required.

The main class provides a menu-driven interface allowing users to interactively perform banking operations, showcasing the practical use of classes, objects, and encapsulation in Java.