[BLOCKED] Appliance console copy keys

This copies fetches keys from a remote machine.

Tested workflows in appliance_console (choosing all the prompts)
Tested in cli

blocked on #550
These come in over the command line arguments.
So if they come in via the constructor or via setters, I wasn't too concerned. Not sure what it buys us to nail down. I do see what you mean. Thoughts?

Have been experimenting with this pattern in kbrock/audio_book_creator#3 - still trying to hone in my [boundaries][] skillz.

[boundaries]: https://www.destroyallsoftware.com/talks/boundaries