Add metadata consolidation feature #110
Description
One may argue it might not be in scope since it's not part of the official spec but:
- it's so helpful! (see, e.g., https://github.com/Huber-group-EMBL/Brillouin-validation)
- there is already a precedent since we chose to support reading consolidated in
zarr_overview(), so we might as well go all the way and support writing it too.