Improve CLI error messages

If a startup failed, e.g. due to allocated ports, and I solve the (docker) problem and run the dev command again, I still have half-started containers and this cryptic error happens:

❌ Error starting development environment: EACCES: permission denied, rmdir 'path-to-my-project/.raclette/virtual/backend/src/appPlugins'

As a dev I would like to know if there are dangling containers.