chore: add lab for arrays to frontend cert (JS only)

[jdwilkin4]

There will be a workshop and lab that will teach campers about arrays and basic array methods.
We need a lab project for them to do right after the workshop.

Campers will know the following so far:

• let
• const
• assignment
• reassignment
• basic string usage
• console.log
• camelCase
• string concatenation using the + operator
• template literals
• str.length property
• bracket notation and retrieving characters from strings
• str.indexOf method
• if/else
• Number()
• Math.floor
• Math.random
• getting a random number from a range
• prompt()
• ===
• if/else if/else
• true and false (truthy and falsey)
• comparison operators
• array basics
• push
• pop
• shift
• unshift

Acceptance criteria

• create a new folder of the project in the frontend-cert/js-projects directory
• add your 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