Use Prettier for code formatting

[sciepsilon]

Working on a codebase that uses Prettier is just... nice. When you read code, it's formatted in a consistent nice way, and when you write code you can have Prettier fix up the formatting instead of manually correcting all your tabs, line breaks, and spaces.

Prettier link: https://prettier.io/

So, let's install Prettier!

• format all files in this repo using Prettier
• create a prettierrc.json and add prettier to the package.json file so that it will automatically be installed (at the correct version) for other LingView devs
• add a Prettier step to the Build & Deploy workflow to ensure all code is prettified before being pushed/merged to the master branch
• if future LingView devs need to be aware of anything Prettier-related, mention it in the New Contributors guide on the wiki and maybe in the Ultimate Guide