feat: add leap year calculator JS only lab

[zairahira]

Checklist:

• [x] I have read freeCodeCamp's contribution guidelines.
• [x] My pull request has a descriptive title (not a vague title like Update index.md)

Closes #427

[jdwilkin4]

@zairahira

So we currently have a rock, paper, scissors game in the DOM manipulation module It will be carried over from the beta JS curriculum https://www.freecodecamp.org/learn/javascript-algorithms-and-data-structures-v8/review-dom-manipulation-by-building-a-rock-paper-scissors-game/step-6

So we can either, remove that from the DOM portion and use your version for the booleans and conditionals module Or covert what is currently into beta into a lab in the DOM module

[zairahira]

I have updated the project to a Leap Year Calculator. The campers would be asked to determine whether the provided year is a leap year or not using conditional statements.

[jdwilkin4]

Also, don't forget to update the folder names to the new project name 👍