Allow to use bioformats2raw to export HCS data

[sbesson]

Fixes #85

Makes the minimal set of changes allowing to re-use the existing infrastructure with bioformats2raw 0.5.0rc2 to generate OME-NGFF including:

• bioformats2raw writing OME-NGFF HCS as defined by the OME-NGFF 0.4 specification, including the bioformat2raw layout with the OME metadata defined https://github.com/ome/ngff/pull/112
• an extra step appending the OMERO metadata to each field of view

To do:

• [ ] current test use --bfpath as the order of getImportedImageFilePaths is not guaranteed and cannot be used directly with bioformats2raw
• [ ] review plate_to_zarr which is updated to allow overwriting the metadata only without rewriting the logic in a separate function.