graphql: Allow to unnest objects

[dennwc]

From discourse thread:

The following query:

{
  nodes(id: spotify:track:6SYdgNzbH6QuFfdlPn3rkc){
    id 
    name 
    artist{name}
  }
}

Produces:

{
	"data": {
		"nodes": {
			"artist": {
				"name": "The Veils"
			},
			"id": "spotify:track:6SYdgNzbH6QuFfdlPn3rkc",
			"name": "Jesus for the Jugular"
		}
	}
}

There should be a way to truncate the results so they are not nested. Something like:

{
	"data": {
		"nodes": {
			"artist": "The Veils",
			"id": "spotify:track:6SYdgNzbH6QuFfdlPn3rkc",
			"name": "Jesus for the Jugular"
		}
	}
}

An be done with a directive on a parent predicate:

{
  nodes(id: spotify:track:6SYdgNzbH6QuFfdlPn3rkc){
    id 
    name 
    artist @unnest {name}
  }
}