Wrap OSC8 formatting into a helper function

Instead of the four separate functions (currently), make a helper:

```
fn format_osc8_link(url: &str, text: &str) -> String {
    format!("\x1B]8;;{url}\x07{text}\x1B]8;;\x07")
}
```
THen could call it like this

```
format_osc8_link(url, "[link]")
format_osc8_link(url, url)
format_osc8_link(url, task_id)
```