Handle gz/zip for any format + preparse h5ad with specific python script

We should :
- handle any file formats potentially being gz, bzip2, zip.
- preparse h5ad with a specific python script to handle the case of asap.epfl.ch/data/datasets/human_testis.h5ad (original: https://cells.ucsc.edu/?ds=testis)
- handle the result of preparsing with websockets to avoid timeouts