Extend GDSDataset Capability to IterableDataset from Torch

[nv-mmanohara]

Description: The GDSDataset currently inherits from PersistentDataset, which in turn inherits from Torch Dataset. We would like to extend the GDS capability to include IterableDataset as well to expedite the loading of data.

Proposed Changes:

1. Create a new class of GDSDataset to inherit from IterableDataset.
2. Ensure compatibility with existing functionalities of GDSDataset.

Benefits:

1. Faster data loading.
2. Improved performance for large datasets.

Additional Context: This change aims to enhance the efficiency of data handling within the GDS framework by leveraging the iterable capabilities of IterableDataset.

[Nic-Ma]

@KumoLiu Please help from MONAI side if @nv-mmanohara faces any problems during development.

Thanks in advance.