Create Doubly Linked List.cpp

[punam01]

Description I've implemented a Doubly Linked List in C++ with various operations including insertion, deletion, display, and checking for emptiness.

Changes

• Implemented the Node class, which represents a node in the doubly linked list.
• Created the DLL (Doubly Linked List) class with insertion, deletion, display, and emptiness checking methods.

This PR is ready for review. Please provide feedback, and if everything looks good, consider merging it into the main branch.

Thank you!