Show full screen output on Wait+Line mismatch

**Is your feature request related to a problem? Please describe.**

Thanks to @mastercactapus we've finally the `Wait` feature, but when waiting for a line on failure it's hard to understand the context as the error is just:

```
failed to execute command: timeout waiting for "Line Username:$" to match Username:$; last value was: >
```

**Describe the solution you'd like**

Other than showing the failed line (ideally in a new line so that's clearer), the whole context should be shown as when using `Wait+Screen`

**Describe alternatives you've considered**
Using `Wait+Screen /Username:\n/` is an option but that doesn't make sure that we're matching the last screen line.

Start by comparing the failure handling for Wait+Line with the existing Wait+Screen behavior described in the issue. Done means a Wait+Line mismatch reports the failed line clearly and includes the full screen context, while still matching the last screen line.

Written by the indexing model from the issue text.