Healthcheck Implementation

I believe our healthcheck implemtnation is currently lacking so just writing some notes on improving it.

I believe ctfcli should treat a solve script as a kind of template. Possibly a Jinja template and populate specific variables and then run the script.

For example we could have something like:

```python
#!/usr/bin/python3
connect("{{ host }}", {{ port }})
```

ctfcli will render this to a temporary file and then execute it.