Field with a "scope" in form values

```js
values = {
  location: {
    country: 'Italy',
    city: 'Milan',
    address: 'Piazza Duomo, 200'
  }
}
```

```js
<FieldScope name="location">
  <TextInput name="country" />
  <TextInput name="city" />
  <TextInput name="address" />
</FieldScope>
```