Epic: Interact with VS Code Browser during workspace load

In our Q1 Hackathon, Anton and Jean-Pierre found out that we can serve the file-system from the content-store without starting the actual container. GitHub is doing a similar technic with github.dev, but use a filesystem that directly connects to GitHub. This isn't too cool in our case, because we want people to look at the state of a workspace (i.e. a prebuilt checkout and state of stopped workspace). Therefore using the content store instead of GitHub as the filesystem provider is much better 🎉 .

Ultimately, we could build a filesystem that first accesses from our content store (read-only), and when the container started delegates to the real filesystem.

Would be cool if this could work from local VS Code as well.