Tunnel group selection when creating new tunnel

### Deployment Type

Self-hosted

### NetBox Version

v3.7.1

### Python Version

3.9

### Steps to Reproduce

1. Section "VPN"
2. Add new tunnel

### Expected Behavior

The form contains a field for selecting the tunnel group.

### Observed Behavior

No such field. A tunnel group can only be assigned by editing an already added tunnel.