Print total calls as part of the stats after closing Echidna

### Describe the desired feature

I track my total calls for reporting later on. It would be nice to have this in the terminal log instead of having to copy it from the TUI and potentially losing it when accidentally pressing ESC.

It could be part of these stats:
```
Unique instructions: 103968
Unique codehashes: 32
Corpus size: 27
Seed: 4563243713121521234
Total calls: 123456789
```