Upgrade JS Tooling

[mrecachinas]

Note: This PR has formatting and linting changes/fixes, so it'll look like a fairly significant one largely touching every file. Further note: Prettier and ESLint will not alter the behavior or execution of the program.

• Replace JS Beautifier with Prettier
• Replace JSHint with ESLint
• Replace Google Closure Compiler with Parcel/Webpack/ESBuild/etc.
• Replace Grunt with package.json NPM directives