add 4 folder with code

[jayambe36]

Fixes issue: This pull request addresses the lack of implementations for several fundamental data structures in the Cosmos repository.

Changes:

Implemented the following data structures:

Graph: Added functionality for basic graph operations in code/data_structures/test/graph/graph.cpp. Heap: Implemented a min-heap structure for efficient priority queue operations in code/data_structures/test/heap/heap.cpp. Queue: Created a standard queue implementation using linked lists in code/data_structures/test/queue/Queue.cpp. Set: Developed a basic set data structure with unique elements in code/data_structures/test/set/set.cpp. Stack: Implemented a stack structure for LIFO operations in code/data_structures/test/stack/stack.cpp. Ensured that all new implementations adhere to the established coding style guidelines for consistency and readability.