Upgrade the webpack-based examples' npm dependencies (move to webpack 5)

[thomasetter]

This is mostly:

$ fd webpack.config.js examples/ | xargs sed "s/mode: 'development'/mode: 'development',\n    experiments: {\n        asyncWebAssembly: true\n   }/" -i

$ fd package.json examples/ | xargs sed 's/serve": "webpack-dev-server/serve" : "webpack serve/' -i

And in each folder touched by the above:

$ ncu -u && npm update && npm update --dev

The weather_report and the webxr examples needed minor adjustments, but besides that everything seems to

The examples seem to work, except ducktype and guide-supported-types which build, but I could not really see anything in the browser.
This was the same for me before this change, please let me know if this is not expected.

[alexcrichton]

Thanks!