Control +C doesn't work

[tjayrush]

Fresh install chifra init --chain gnosis chifra export gnosis.eth

try to control + c -- doesn't quit. The keystroke is noticed, but the loop does not stop.

I don't think this particular code path ever had control+c handling in it. The chifra init code does, and that still works fine, but this is a different code path.

[tjayrush]

But, it's even worse than that. While the Control+C appears to stop the current download, we end up with partial (corrupt) files.

We need to grab the same code that protects chifra init and use it in chifra export when downloading previously downloaded chunks.