refactor: Replace Rollup with Vite (#2656)

This is a high risk change: every byte the card ships is emitted by a
different bundler, minified by a different minifier, and every
stylesheet is compiled by a different sass. The intent is that the
card's behaviour is unchanged.

**Significant development win**: Build time drops from 24s to 1.1s 🎉 

Also adds a test suite ('dist') that runs against the built bundle.

docs/developing.md

@@ -24,6 +24,16 @@ Resultant build entry file will be in `dist/advanced-camera-card.js`. This could
 installed via the [manual installation
 instructions](advanced-installation.md?id=manual-installation).
 
+To rebuild as the source changes:
+
+```sh
+$ yarn start
+```
+
+This writes to `dist/` just like a normal build so that Home Assistant reading
+the card from a path on disk picks each rebuild up. To have Home Assistant read
+from a URL instead, use `yarn preview` which serves `dist/` on port 10001.
+
 ## Releasing
 
 ### Release Philosophy