Add startup wizard #91

I did a demo of this repo and realized I forgot to use the --sp-keys-file startup option. We have a handful of other options like data directories and so on. I think a simple binary that walks through the options and prompts the user to select their preferences

Something like:

> cargo run --bin wizard

which network would you like to run on?
> signet
   bitcoin 

where should data be stored?
> ~/.kernel-node

would you like to import keys?