fixes #7867: container creation wizard now tracks state in dedicated objects

```try(:split)``` is not needed here, in fact it will break the container creation, for instance an entrypoint of "/bin/ping" and a command of "google.com" will be

```
entrypoint : "---\n- /bin/ping\n" 
command: "---\n- google.com\n" 
```

which will not work when starting up the container. Instead, it should be just