Provide API to access a DelayedImage or DelayedVideo
the CocoDataset class should provide an API for a delayed image or video.
Currently there is an experimental delayed image loader. That should be extended to detect if a file is a tiled tiff and perform the appropriate subregion loading commands via rasterio or gdal (start with gdal?)
There should be a delayed video as well.
The existing Delayed classes may need to be optimized via pymbolic (see ndsampler/dev/symbolic_delayed.py).
Eventually, ndsampler should access this API.