Closes: #384

This pull request introduces a C++ implementation of the Matrix Chain Multiplication (MCM) problem. This is a classic algorithm that serves as a perfect introduction to the Partition DP pattern, a concept that was previously missing from the dynamic programming section.

This pattern is essential for solving optimization problems where a key task is to find the best possible split or partition point. The solution uses a bottom-up (tabulation) approach to achieve a time complexity of $O(n^3)$.

📝 Summary of Changes

• Added matrix_chain_multiplication.cpp: A new file in CPP/algorithms/dynamic_programming/ containing the complete solution.
• Implemented Partition DP: The core logic involves a 2D DP table where dp[i][j] stores the minimum cost to multiply matrices from i to j. The solution iterates through all possible partition points to find the optimal cost.
• Included Demonstration: A main function is provided with a standard test case to verify the algorithm's correctness and demonstrate its usage.

✨ Key Features

• Introduces a New DP Pattern: This PR adds the fundamental Partition DP technique to the repository's collection.
• Classic Interview Problem: MCM is a well-known problem asked in interviews to test a candidate's understanding of dynamic programming fundamentals.
• Optimal and Well-Commented: The code is clean, efficient for the problem's constraints, and includes detailed comments explaining the DP state and transitions.