[hiopy] Add an example and test for Zarr3 sharding

Motivation

Task description

• add an example for zarr3 sharding
• test the example in the CI
• point to it from the documentation

Definition of done (Max 3 points)

added hiopy label

mentioned in merge request !37 (merged)

assigned to @m301120

mentioned in merge request !43 (closed)

mentioned in merge request !52 (merged)