Operator doesn't show public field if network is not specified (beta branch)

As the field "network" is optional, if you don't declare it, all the fields inside of it aren't declared as well. Then, if you create a custom resource without "network", everything works, but the public field shown when you get challenges is empty.
Example:
Custom Resource:

```
apiVersion: kctf.dev/v1alpha1
kind: Challenge
metadata:
name: mychal
namespace: mychal
spec:
image: "some_image"
deployed: true
// we don't have the network part
```

Get challenges:
```
name health status deployed public
mychal disabled Running true
```