IRC message layout: mIRC-like appearance

### Your use case

#### What would you like to do?
The current IRC (experimental) layout appears to have two columns: "Time+Username" and "Message contents".

In order for longer usernames to fit on the screen, the sliding divider between columns has to be moved right somewhat.

I would prefer a more mIRC-like layout where everything is left-justified without wasted space.

So instead of:

```
12:34 Foo | Hello!
12:34 VeryLongUserName | Hello there
12:35 Foo | Hi. How are you?
12:35 VeryLongUserName | Fine thanks.
```

It would look like:

```
12:34 Hello!
12:34 Hello there
12:35 Hi. How are you?
12:35 Fine thanks.
```

#### Why would you like to do it?

To me chat is more readable this way. Different user names taking up different amounts of space helps my eyes quickly identify which messages belong to which user in the conversation.

#### How would you like to achieve it?

An option in the Appearance settings which removes the sliding column divider and formats the messages in the above example style.

### Have you considered any alternatives?

_No response_

### Additional context

_No response_