Fix type checks in CartoDB

Removed state from super call options because super doesn't use it.
Defined CartoDBLayerInfo response type.

src/ol/source/CartoDB.js

@@ -31,6 +31,12 @@ import XYZ from '../source/XYZ.js';
  */
 
 
+/**
+ * @typedef {Object} CartoDBLayerInfo
+ * @property {string} layergroupid The layer group ID
+ * @property {{https: string}} cdn_url The CDN URL
+ */
+
 /**
  * @classdesc
  * Layer source for the CartoDB Maps API.
@@ -48,7 +54,6 @@ class CartoDB extends XYZ {
       maxZoom: options.maxZoom !== undefined ? options.maxZoom : 18,
       minZoom: options.minZoom,
       projection: options.projection,
-      state: SourceState.LOADING,
       wrapX: options.wrapX
     });