Convert a Single Command CLI into a Multi Command CLI with Oclif and TypeScript

Heavy duty CLI's like gatsby and npm do more than one thing. The convention is to namespace them with a command name after the CLI name, like gatsby new or gatsby build or npm install or npm uninstall. We should be comfortable converting our single purpose CLI's into multi command CLI's as our needs grow, as well as understand how to share logic between commands to keep code DRY.