Add Binary Search Tree Implementation.

[Nishithaaa0905]

This pull request adds a beginner-friendly implementation of a Binary Search Tree (BST) in JavaScript.

Features included:

• insert(value): Adds a new value to the tree
• search(value): Checks if a value exists in the tree
• inOrderTraversal(): Returns all values in sorted order

This implementation is designed to help beginners understand how BSTs work and practice basic tree operations. Example usage is included for clarity.