Return actions as structured json with named keys

[slinlee]

Right now all the actions are returned in a flat array. This is easy to integrate into AnyLogic pathmind helper and probably python simulations. But it will be difficult to use from a webapp trying to integrate with a policy.

example:

{"action":[0,3,5,1]}

vs

{ "action": {
    "agv1_movement": 0,
    "agv2_movement": 3,
    "target_value": [ 5, 1]
  }
}

[slinlee]

This would depend on PathmindAI/nativerl#351

[maxpumperla]

@slinlee we can do that, no problem. I guess the nativerl issue is the bigger one here. I'll try to make this optional and ensure backward compatibility (no reason not to).