**Describe the changes you'd like** The Calculator isn't having a direct function to find a square,cube,cube root and square root. Adding these functionalities in the PR. <!---Read the contributing guideline--> <!--checkmark the below box, by adding an 'x'--> - [*] I follow the [Contributing Guideline](https://github.com/Shweta2024/JavaScript-Projects/blob/master/ContributingGuidelines.md) of JavaScript-Projects.