Heap's Algorithm for generating all Permutations

[nidhi-2619]

Feature description

It is an decrease and conquer algorithm which is used to generate all the permutations of a given sequence.

[tianyizheng02]

We already have implementations of Heap's algorithm in heaps_algorithm.py and heaps_algorithm_iterative.py

[tianyizheng02]

Closing this issue, if you have an implementation that's different from the existing ones or if you want to improve upon the existing ones, you're welcome to open a PR.