WIP: Add Ember

[NullVoxPopuli]

Very WIP. I open PRs early as a way of keeping track of what I have in progress.

Resolves https://github.com/webcomponents/custom-elements-everywhere/issues/237

• [x] meta
  • [x] no open issues regarding web-component compatibility
  • [x] write summary
  • [x] define expected results
• [x] Components' Implementation
• [x] Basic Tests Pass
• [x] Advanced Tests Pass
• [ ] Integrate into reporting / infra

Of note, ember currently uses Vite, not webpack, so we have to make some tweaks to shoehorn a vite build into this repo's way of using webpack -- shouldn't be too bad tho.

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