V3 Consolidated Metadata

[joshmoore]

follow on to: https://github.com/zarr-developers/zarr-python/pull/1142 background reading: https://github.com/zarr-developers/zarr-specs/issues/136

I would like to propose that we remove the machinery for consolidated metadata in the current V3 implementation in favor of an upcoming specification. This would include:

• dropping zarr._storage.v3.ConsolidatedMetadataStoreV3
• disallow version=v3 in zarr.convenience.consolidated_metadata

[jhamman]

Noting that what we really need is someone to work on:

• [ ] A spec for consolidated metadata in v2
• [ ] A spec for consolidated metadata in v3
• [ ] An implementation in the active v3 branch

Marking this with a help-wanted label.