Differences between StoreToZarr and xbeam's ChunksToZarr

[cisaacstern]

Re-reading #376 I note that there is discussion there about possibly using ChunksToZarr from Xarray Beam. In the end, we have our own StoreToZarr transform. There has been ongoing discussion at coordination meetings lately of increasing alignment between Xarray Beam and Pangeo Forge, so before closing #376 just wanted to open this issue as a place to continue discussion on this topic.