Move top-level typedefs to typedefs.js

With one exception, those directly in the `ol` namespace can be moved without problem.
Some left-over goog.requires are also removed.

src/ol/attribution.js

@@ -4,13 +4,6 @@ goog.require('ol.TileRange');
 goog.require('ol.math');
 
 
-/**
- * @typedef {string|Array.<string>|ol.Attribution|Array.<ol.Attribution>}
- * @api
- */
-ol.AttributionLike;
-
-
 /**
  * @classdesc
  * An attribution for a layer source.