Partial Zarr Directory Updates in Dandi and LINC

Cc @dstansby @kabilar @satra @yarikoptic @waxlamp @balbasty

In the LINC project, @dstansby encountered a scenario where an update was requested for a portion of a Zarr directory.
Currently, DANDI and LINC treat a Zarr directory as a single object tree, requiring the entire directory to be downloaded even for updates that only modify specific pieces.

Downloading the entire Zarr directory can be inefficient, especially for large datasets where only a small portion needs updating.

This issue's purpose is to capture the need for mechanism to allow for partial updates of Zarr directories within Dandi and LINC.

Analagous, @satra suggested the initial usage of [zarrita](https://github.com/scalableminds/zarrita) to explore elements of sharding, with perhaps the LINC project as a place to test