Push spraggins to google cloud

[manzt]

The linnarsson update in v.0.23 ignores all .zarr files from syncing with AWS. This is my mistake. We haven't been using the Spraggins dataset in Vitessce (yet), but this change prevented spraggins.ims.zarr from being pushed in the most recent release.

This PR updates the destination URL for the spraggins IMS dataset to google cloud storage, explicitly pushes the zarr array there, and updates some oddities that we've run into trying to get these data to render in Viv.

• Adds a transform and domain keys to spraggins.ims.json. -- transform: includes scale and translate keys to position image in renderer. This could include other transformations in the future. -- domain describes the domain of values in the datasets, generally [0, max]
• Changed the dtype to uint32 rather than int32

I think we should move towards parsing the zarr metadata in the future, so I have mirrored the changes in spraggins.ims.json to .zattrs and we can work towards this in the future.

[ilan-gold]

I like the mirroring of the changes, thanks for that.