Added Radix and implemented CSS Modules for styling

Experiment with Radix and CSS Modules.

Overview:

• ui/src
  • This adopts Radix. The PoC UI looks like this now: https://git.drupalcode.org/project/experience_builder/uploads/e22b33df833e9ac9ec618db347bb4cd8/Screenshot_2024-05-21_at_10.40.45_AM.png
  • It also adopts CSS modules
  • It also configures stylelint, and updates CSS to make that pass
• src/Controller + *.libraries.yml + *.routing.yml
  • It also gets rid of rendering this inside html.html.twig, and instead makes the PoC UI the entire viewport.
• submodules/eb_vite
  • In doing the previous bullet, the eb_vite integration broke, so that had to be updated.
• *.module
  • Make it easier to find the UI.
• *.info.yml
  • This failed to install on D11.

☝ After this is in, the most basic foundations for productively collaborating on the UI will have been laid.