Implement ip scp server enable support

**Description**  
Can you please implement support for enabling scp server?

**show running-config | i scp**  
This is part of the running config:

```


ip scp server enable
```

**json path: .data["Cisco-IOS-XE-native:native"].ip.scp**  
This is the restconf-json formatted running config:

```
{
  "server": {
    "enable": [
      null
    ]
  }
}
```
