Comment test - Githubissues

In this pull request I made the following changes:

Put commentCounter function in a separate module called commentCounter.js
Wrapped the event listeners in comment.js in a function called popUpListeners
Imported the popUpListeners function to fetch.js and called it to register the event listeners.
Added a test for commentCounter function called commentCounter.test.js using Jest.

christianonoh / film-fussion