Add Binary Tree Traversal Algorithms: Inorder, Preorder, and Postorder

[AshutoshSingh058]

Overview

This PR adds implementations of the three primary binary tree traversal algorithms:

• Inorder Traversal (Left, Root, Right)
• Preorder Traversal (Root, Left, Right)
• Postorder Traversal (Left, Right, Root)

These traversals are fundamental for understanding and manipulating binary trees.

Details

• Implemented using recursive approaches for clarity.
• Traversals return a list of visited node values.
• Supports trees with integer node values.
• Code is modular and easy to extend to iterative versions or non-binary trees.

Example

For the binary tree:

[AshutoshSingh058]

please assign the issue to me and would love to contribute

[Puneetha00]

Can you please assign this to me?