Added image data value to 'forEachLayerAtPixel' method callback

The update has been added to the docs for all 'forEachLayerAtPixel' definitions
and currently returns null for non-supporting definitions. ol.Color typeDef
was also updated to support Uint8Arrays & Uint8ClampedArrays as it is the
reference type for the addded argument #5586

src/ol/renderer/map.js

@@ -180,7 +180,7 @@ ol.renderer.Map.prototype.forEachFeatureAtCoordinate = function(coordinate, fram
 /**
  * @param {ol.Pixel} pixel Pixel.
  * @param {olx.FrameState} frameState FrameState.
- * @param {function(this: S, ol.layer.Layer): T} callback Layer
+ * @param {function(this: S, ol.layer.Layer, ol.Color): T} callback Layer
  *     callback.
  * @param {S} thisArg Value to use as `this` when executing `callback`.
  * @param {function(this: U, ol.layer.Layer): boolean} layerFilter Layer filter