Add REST API integration to set of defaults?

[jmichaelward]

Glancing at the main plugin class, I see we have a set of sensible defaults for creating a new post type, but nothing for WP REST API settings (e.g., "show_in_rest"). Surely, this can be overridden via the arg_overrides parameter, but I'm wondering if it makes sense to be explicit here to indicate that CPTs can support the REST API. If that's the case, does it make sense to turn on REST API support by default?