minify CSS and JS files

[immnk]

Is your feature request related to a problem? Please describe.
As webpack-testing user, I need the production build to contain minified JS and CSS files so that files are less spacious and load faster.

Describe the solution you'd like
Using webpack plugins such as optimize-css-assets-webpack-plugin and terser-webpack-plugin for CSS and JS respectively.

Describe alternatives you've considered
N/A

Additional context
N/A