[docs]: rewrite ux-dot CSS

[bennypowers]

If you'd ask me, I'd say we're overdue to refactor the UX-DOT CSS:

• remove SCSS
• remove BEM-style selectors
• tokens everywhere
• maybe adopt Declarative Shadow DOM on ux-dot
  • Mozilla's support for the feature is now positive
  • WebKit shipped it
  • we'd apply the polyfill and use an 11ty transform to stamp custom elements with DSD templates
  • we'd show other teams it's possible

The advantages we stand to gain are:

• smaller node_modules
• fewer dependencies
• faster builds
• easier to grok CSS
• more dogfooding
• provide an examplary use of RHDS tech

Originally posted by @bennypowers in https://github.com/RedHat-UX/red-hat-design-system/issues/638#issuecomment-1467407021

[bennypowers]

cc @dcaryll @markcaron @zeroedin @coreyvickery @marionnegp

[coreyvickery]

@bennypowers Sounds cool. I am prepared for things to break a bit temporarily, but if that means sleeker code in the end, so be it.

[bennypowers]

ideally we could do this bit by bit, focusing on specific items, so that review wouldn't be too onerous

[marionnegp]

@bennypowers, yes please! I'd be up for helping where I can too.

[zeroedin]

We should pair this with moving reusable parts to .webc as well, further scoping the styles to components and overall less clutter in the base styles.