Refactor Webpack Configs

[rdig]

Description

This PR started it's life as a way to do cache-busting in new deployments by inserting a content hash in the name of the outputted bundle.

In the end it turned into:

• Added content hash string to the outputted chunks (in production)
• Split the bundle into three main parts: main, libs, vendors (in production)
• Vendors has the benefit on not changing that often, meaning it can be cached by the clients
• Refactored the webpack configs for saner maintenance (dev and production now inherit from base, and only add in they're required config declarations)

The next step in this saga, is to add in code splitting, ... at some point.

New stuff

• Added clean-webpack-plugin package
• Added new webpack base config, from which all else inherit
• Added new webpack prod config, for production env builds
• Added new webpack dev config, for development env builds and out of which the yarn dev server runs

Deletions

• Removed old webpack.config.js development config
• Removed old webpack.config.prod.js production config

Screenshots

[ceolson01]

This looks good to me - nice improvements. Also, thanks for commenting so thoroughly for our future selves 👍