Configuration

Currently there are no configuration options for cucumber-node - everything hangs off what `node --test` does from its own arguments.

But we'll need some configuration options sooner or later. Examples:

- https://github.com/cucumber/cucumber-node/issues/9
- https://github.com/cucumber/cucumber-node/issues/10

It's fair to assume that users will want to:

- Have some options that always apply, in a file
- Override those options run-by-run, sometimes

As with other things, we want to lean into Node.js conventions and not reinvent the wheel. Some options (multiple choice):

- Support environment variables, and encourage users to lean into Node.js support for `.env` files
- Use the nascent Node.js config file
- Have our own config file