Restore cursor if dialoguer Ctrl+C-ed

[itowlson]

Fixes #2557.

At the moment, this prints Error: read interrupted after the Ctrl+C. I've tried some of the suggested fixes and they have either had the same quirk, or not fixed the problem, or both. So for now I'm accepting that ugliness as a compromise. Better offers eagerly accepted!

This PR sets the Ctrl+C handler up at the entry to every command that uses dialoguer hidden-cursor functions. This is safer than putting it near the point of use, because you can only set a Ctrl+C handler once per process; and we cannot put it at the top of the whole program because some commands need different/extra Ctrl+C processing (e.g. spin up tearing down triggers). This can result in setting up a handler that might never be needed (and it's not 100% clear if that could have unexpected side effects).

There is code duplication here: we could move it into common or terminal but that would introduce new dependencies into those crates, which are used quite widely. But maybe it's worth it.