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: `bot` 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://nlux.ai/images/demos/persona-user.jpeg'
        }
    });
```

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

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