feat(storage): support partial reads

[manzt]

Introduces the Readable.getRange method, which can be optionally implemented by a store to support partial reads. The RangeQuery param is inspired by the HTTP Range header. Allowing the suffixLength query means the store can decide the best way to return the final N bytes from a file.

const store = new FetchStore("http://localhost:8080/data.zarr");
await store.getRange("/foo.json", { suffixLength: 100 });
await store.getRange("/foo.json", { offset: 10, length: 20 });

cc @andersy005