Loads a new tile region or updates the existing one. Creating of a new region requires providing both geometry and tileset descriptors to the given load options, otherwise the load request fails with RegionNotFound error. If a tile region with the given id already exists, it gets updated with the values provided to the given load options. The missing resources get loaded and the expired resources get updated. If there no values provided to the given load options, the existing tile region gets refreshed: the missing resources get loaded and the expired resources get updated. A failed load request can be reattempted with another loadTileRegion() call. If there is already a pending loading operation for the tile region with the given id the pending loading operation will fail with an error of Canceled type. Note: The user-provided callbacks will be executed on a TileStore-controlled worker thread; it is the responsibility of the user to dispatch to a user-controlled thread.
Returns a Cancelable object to cancel the load request