Allow opting out of typedefs

Code generated by the CLI will include the @enhance/types package and add code comments that activate VS Code's Intellisense.

It would be good for power users to have a setting in their ~/.begin/config.json to disable the automatic adding of types.

Ryan Block: Hmm, yeah! Perhaps maybe also a settings command of some kind so one doesn't have to muck around in the file?

From: https://github.com/beginner-corp/cli/issues/81