When returning to the app in a chat and the keyboard was open, the chat isn't scrolled down

## Steps to reproduce
1. Open a chat
2. Select the text view to send a message which opens the keyboard
3. Send the app to the background
4. Return to the app
5. The chat is open and the keyboard is up, but the chat is not scrolled down in a way that the keyboard covers its last messages

### Expected behaviour
The chat is scrolled down and all the last messages are visible.

### Actual behaviour
Not that, see above.

## Device information

**Device:** iPhone X

**iOS version:** 16.1.1

**Talk version:** 15.1.1

## Server information

**Nextcloud version:** (see admin overview page: `/index.php/settings/admin/overview`) 25.0.1

**Talk version:** (see apps admin page: `/index.php/settings/apps`) 15.0.1

**Custom Signaling server configured:** yes/no and version (see talk admin settings: `/index.php/settings/admin/talk#signaling_server`) no

**Custom TURN server configured:** yes/no (see talk admin settings: `/index.php/settings/admin/talk#turn_server`) yes

**Custom STUN server configured:** yes/no (see talk admin settings: `/index.php/settings/admin/talk#stun_server`) yes

### Server log (data/nextcloud.log)

```
Insert your server log here
```

Reproduce the issue in an iOS chat by opening the text view, sending the app to the background with the keyboard open, and returning to it. Start by tracing the chat view's keyboard and app-background/foreground handling; done means the chat is scrolled so the last messages remain visible when the keyboard is shown.

Written by the indexing model from the issue text.