Only render tiled GeoTIFFs

[mojodna]

Check src.driver == "GTiff", src.profile["tiled"] == True, src.profile["blockxsize"] == src.profile["blockysize"].

This will prevent an excessive number of reads due to pixels laid out in strips vs. blocks or non-GeoTIFF formats (that may require full reads). It will accept non-COGs, as long as the layouts are conducive to partial reads.