Cover zarr assets in `_maybe_validate_asset_metadata`

[jjnesbitt]

Follow up from #1352 (comment)

Currently, when creating/updating an asset we conditionally validate metadata. This doesn't currently include zarrs, but in theory should. The current code for the condition in maybe_validate_asset_metadata could be updated to reflect this:

if asset.is_zarr:
    if asset.zarr.checksum is None:
        return
else:
    blob = asset.blob or asset.embargoed_blob
    if blob.sha256 is None:
        return

Similarly, when the calculate_sha256 task completes, it kicks off asset metadata validation. The same thing should be done for all relevant assets at the end of ingest_zarr_archive.

[jjnesbitt]

This has been demonstrated to occur in the wild, and results in any zarr asset added to a version being perpetually in a PENDING status.

[dandibot]

🚀 Issue was released in v0.3.24 🚀