Use the new action during app load.
Performance note:
- When user loads a new version of the app, it should be slightly slower because now they need to do two requests instead of one
- If the js is already cached it should be more or less the same
But these changes allow us to do an optimization for case (1) -> we could first download just enough to start rehydration and fetching of the initial redux state, and do it concurrently to the fetching the rest of js. I'm going to create a task for this later because it would require more changes.