Balanced Binary Search Tree constructor

[rostow]

It would be nice to add a method to the BST class so that given an unsorted array of integers a balanced BST is constructed. I'm not sure whether it is already in the repo but I have not been able to find it. I'd be happy to take care of it if you find it interesting :)

[OmkarPathak]

@rostow thanks for the feedback. You can open a Pull Request if you are interested in contributing 😄

[AhmedOssama22dev]

Check my pull request
#46 (comment)