Expose metadata from all sources in multi-source Zarrs

[frasercl]

Description

Currently, in multi-source OME-Zarr images, only the first source's metadata is represented in certain ImageInfo fields.

Expected Behavior

Metadata for all channels should be accessible.

[jennifermccarty]

Cameron - related issue on Vol-E core data. Asked to do for Nuc Morph. Dan - add data to the back end (possibly a second ticket).