Build first version of confgen component

[norswap]

As per this design document, we intend to have a confgen component that is responsible for outputting a master chainconf configuration file.

The goal of this issue is to create the MVP version of this component, which asks the bare minimum questions on a CLI interface to output the chainconf file. Most configuration value should be populated with defaults.

It would be good to ask at least one or two user inputs questions so we can see how the query flow, validation, etc... will work (and otherwise, a static json file might have worked just as well).