[#81669] Backport upstream OpenLayers TileManager

Backport of TileManager form upstream OpenLayers.
Comes from https://github.com/openlayers/openlayers/blob/cd2cd9/lib/OpenLayers/TileManager.js.
Merge pull request #172 from juanluisrp/81669-add-tilemanager

[#81669] Backport upstream OpenLayers TileManager