Mock API by pointing to Open API spec

It would be very cool if you could point the dev proxy to some openapi spec url and have it mock that api.

And as an extra feature it should use AI (bring your own key) that checks the object type and tries to mock reasonable data.

So if you mock a `/users/{id}` endpoint it would generate a reasonable response for a `givenName` or a `mail` property.

The generated response should be saved for economic reasons off course.