WIP: upgrade to Webpack 5

[apaleslimghost]

Phase One of my Secret Page Kit Project

still to do:

• [ ] import paths aren't working with nested workspace dependencies for examples tests
• [ ] clear webpack deprecation warnings
• [ ] pretty sure we can get a lot more performance out of webpack by tweaking options
• [ ] update the rest of the outdated dependencies
• [ ] test in a real app
• [ ] Phase Two 👀