[Long term] Replace popover/tooltip positioning logic with new CSS anchor positioning

⚠️ The new CSS anchor positioning spec is **not yet implemented** by all browsers and its API is **not yet stable**. This functionality is not ready to use within the next ~year or so, but we should keep an eye on its progress and be ready to replace our popover and tooltip components with it once it's ready to use.

A helpful preview of its functionality in Chrome, well worth checking out: https://developer.chrome.com/blog/tether-elements-to-each-other-with-css-anchor-positioning/

### Feature status:

- https://caniuse.com/css-anchor-positioning
- https://www.w3.org/TR/css-anchor-position-1/
- https://chromestatus.com/feature/5124922471874560