Support 10X Cell Ranger HDF5 format

[arteymix]

The Cell Ranger tool can also produce HDF5 outputs. I'm not sure how common that is however on GEO.

Reference: https://support.10xgenomics.com/single-cell-gene-expression/software/pipelines/latest/advanced/h5_matrices

[arteymix]

It seems to be very uncommon, but the new RNA-Seq pipeline will produce this output, so it might make loading data a bit faster to have it implemented.

[arteymix]

With #1511, we will have the capability of calling Cell Ranger Python utilities to read their HDF5 file format.