chore: convert random background color changer workshop into lab

[jdwilkin4]

We currently have this debugging project in the beta JS curriculum
https://www.freecodecamp.org/learn/javascript-algorithms-and-data-structures-v8/#learn-basic-debugging-by-building-a-random-background-color-changer

I think it would work better as a lab then a workshop.
Let's convert this workshop to a lab.
Review the steps and see where we can create user stories.
We will have campers just start with the completed broken project with errors and then the user stories will be about fixing those errors so it works properly.

Acceptance criteria

• create a new folder called random-bg-changer app in the frontend-cert/js-projects directory
• add the completed project in an script.js file in that new folder
• create a markdown file for your proposed user stories. You should call it user-stories.md and place it in your new project folder