more robust zarr reading including time selection and ome metadata

## Use Case

We want to be ready to handle larger zarr datasets in the viewer. If a time series is loaded, make sure the time selection works via the testbed ui.

## Solution

This will be an incremental update to build out more generality for zarr loading of TCZYX data - allow time selection for time series, and improve ome metadata reading. Possibly also add ability to select from multiscale data.