In JavaScript, you can define the user persona by calling `withPersonaOptions` when creating the `AiChat` component.
The `withPersonaOptions` function takes an object with two properties: `assistant` and `user`. The `user` property is
what you use to define the user persona, as shown in the example below.

```javascript
const aiChat = createAiChat()
    .withAdapter(adapter)
    .withPersonaOptions({
        user: {
            name: 'Alex',
            avatar: 'https://docs.nlkit.com/nlux/images/personas/alex.png'
        }
    });
```

The object passed to the `user` property should match the following interface:

```typescript
interface UserPersona {
    name: string;
    avatar: string | HTMLElement;
}
```
