Support reading new S3 Artifacts

[philippotto]

When these new formats are implemented in vx, we should be able to read them in wk, too:

• Agglomerate File Read Zarr Agglomerate Files #8633
• Mesh File Read Zarr Mesh Files #8682
• Segment Index File Read Zarr Segment Index Files #8711
• Connectome File WIP: Read Zarr Connectome Files #8717
• Optional: Cumsum File (perf optimization for reading agglomerate files)

[philippotto]

@fm3 I assigned you for this issue, but feel free to re-assign. We should probably tackle the formats sequentially and can only start once the vx side is done.