Convert modules to standardized module system

Currently our code is still using the legacy [CommonJS module system](https://nodejs.org/api/modules.html#modules-commonjs-modules), instead standardized [ECMAScript modules](https://nodejs.org/api/esm.html#modules-ecmascript-modules) should be used. This makes the code more familiar to JavaScript developers not familiar with the old module system, and helps future proof the code so that we can upgrade our dependencies.