Post should still be visible in REST-API with slug lookup

[pkreissel]

Is your feature request related to a problem? Please describe.

Currently when you use Wordpress API to lookup an unlisted post using:

https://example.com/wp-json/wp/v2/posts/?slug=this-is-the-slug

The response is empty.

Describe the solution you'd like

However it would be better if the response would still show the post, but with an "unlisted" attribute.

Describe alternatives you've considered

There are none.

Additional context/screenshots

NA