Description

This PR creates a modal component and an implementation of it in Storybook.

Fixes #46

How to test?

"npm run storybook" to see the implementation of the modal

[x] I have performed a self-review of my own code
[x] I have followed the name conventions for CSS Classnames and filenames, Components names and filenames, Style filenames, if you are in doubt check the the project README.MD and here https://github.com/HackYourFuture-CPH/curriculum/blob/master/review/review-checklist.md
[x] I have commented my code, particularly in hard-to-understand areas, if you code was simple enough mark the box anyway
[x] I have made corresponding changes to the documentation, if you code was simple enough mark the box anyway
[x] This PR is ready to be merged and not breaking any other functionality