feat: Add Morris In-Order Traversal to BinaryTreeTraversal

[asmit27rai]

Description

This PR adds the Morris In-Order Traversal algorithm to the BinaryTreeTraversal class. Morris Traversal is a space-efficient algorithm for performing in-order traversal of a binary tree without using recursion or a stack. It achieves O(1) space complexity by temporarily modifying the tree structure using threaded binary trees.

Changes

1. C++ Backend:

   • Implemented the morris_in_order_traversal method in the C++ backend.
   • Exposed the method to Python using PyMethodDef.

2. Python Binding:

   • Updated the Python binding to include the morris_in_order_traversal method.

3. Unit Tests:

   • Added unit tests for Morris Traversal in the test suite.
   • Verified compatibility with both Python and C++ backends.