Feature: Adding Introsort implementation in JS.

[Lakhan-Nad]

We can add the sort routine used by std::sort in c++ standard library in JavaScript.
Introsort is a hybrid sorting algorithm that uses quicksort and heapsort. The C++ STL takes it a step further and adds insertion sort to it for small length arrays.
We can add a method is JS for introsort which takes array and a compare function as parameters and sorts the array.