Another change in snowpack@3 caused this bug. It's not actually a bug in snowpack. Previously snowpack was keeping its list of installed packages in a global cache. In 3.3 it stopped doing so. We were accidentally relying on that global cache to be able to resolve dynamic components.
This fixes it so that we use the frontend snowpack instance to resolve dynamic components. Doing so means they are available when we try to load them.
Previously dynamic component URLs were being resolved client-side in a weird way that only worked during dev. This change makes them handle during compilation, so it works in both (and improves readability of the dynamic import output).
* Add support for React components.
This adds support for react components via a new `extensions` config in astro.config.mjs. In the future we can extend this to do things like look at the import statements, as Snowpack does.
* Fix the tests
