zarr_content_read: include sizes for the "files" (and possibly "directories")

[yarikoptic]

motivation: dandi/dandi-cli#923 (comment) -- in dandi-cli, to possibly avoid relatively expensive checksumming of the content to decide either a (changed) file within zarr needs to be reuploaded, we first check the size(s) of the file. If that one changed -- we know that we need to reupload even without computing its checksum.

It would be helpful if that API endpoint also returned sizes of the files (if it can do it without extra runtime penalty)

[dchiquito]

I am addressing this in #937

[dchiquito]

Reopening this to track the work required to update the dandischema version to 0.6.0, which includes dandi/dandi-schema#120

[jwodder]

Relatedly, if the endpoint also included "last modified" dates and S3 keys (and possibly also S3 version IDs) for Zarr entries, that would help reduce the number of requests needed by the backup script.

[dandibot]

🚀 Issue was released in v0.2.3 🚀