`miren env set` should watch deploy and print routes like `deploy` and `rollback` do

miren env set triggers a new version deployment, but unlike miren deploy and miren rollback, it exits immediately after setting the vars without watching the deploy progress or printing the routes at the end.

Would be nice if it followed the same pattern — watch the deployment roll out and show the app URL when it's done. Makes it easier to verify things are working without having to run miren app status separately.