Exploration of libraries for loading Zarr data

[katamartin]

As mentioned in our blog post, we're currently using our own zarr-js implementation, but there are other existing (and other emerging!) implementations worth exploring for the sake of unifying around an approach to loading Zarr in the browser.

So far, we've established that zarr-js is a good fit because it meets our most pressing needs:

• first class support for consolidated metadata
• string support
• support for Zarr v2 spec
• reasonable add to build size in our Next.js

We've also explored integrating with Zarr.js (see PRs), but decided to stick with zarr-js because it currently handles our first two needs above well.

We're keeping this issue open to track our explorations in this area as well as track any relevant developments in other Zarr-in-JavaScript libraries!