Webpack setup is deprecated

## Description

![image](https://user-images.githubusercontent.com/12001504/69461138-77a8bc80-0d3b-11ea-9aad-c1e7525bb6f4.png)

## Motivation

Our `setup` is what allows `env.js` to be overridden for local development.

## Implementation

* [x] migrate to `before`
