Update to webpack 5

[theimowski]

I recall there were same issues for Feliz and Webpack 5 - https://github.com/pmmmwh/react-refresh-webpack-plugin/issues/330 Not sure if it relates to stuff we have in template though @Zaid-Ajaj

[mattgallagher92]

Summary from a discussion between me, @theimowski and @MangelMaxime:

• react-refresh requires that code follows certain conventions, such as not exposing types or functions that are not React components
• Feliz code that generates JavaScript code that doesn't follow those conventions will not be able to benefit from react-refresh
• In that case, the behaviour will be just the same as it was for webpack 4 (tab reload)

In summary, there is no problem moving to webpack 5. fulma-demo is already using webpack 5, so we can use that as a template.

[theimowski]

Closed by #485