Update Webpack

[R4356th]

Expected Behavior

We are using the latest version of webpack.

Actual Behavior

We are using webpack 4.

Steps to Reproduce

Check package.json.

Operating System and Browser

N/A

Checklist

• Update webpack-cli (build(deps-dev): bump webpack-cli from 3.3.12 to 4.7.2 #20)
• Update webpack itself
• Update plugins and loaders
• Adjust configuration
• Resolve Switch from UglifyJS to Terser #2
• Resolve Migrate to Webpack 5's Asset Modules #31