Upgrade embroider, use vite

A bunch has changed since we enabled this: https://github.com/embroider-build/embroider/commit/73d997d5d7389a43706a3dc3d2159b99f66b933a.

Let's try to use the new vite adapter and see if that makes our builds faster

https://github.com/mainmatter/ember-vite-codemod