This commit introduces two improvements:

1. DirectML acceleration:

    - Added support for running optimum commands on DirectML hardware (Windows only) using the --device dml flag.
    - Automatically sets the device to torch_directml.device() when the flag is specified.

2. Improved device handling:

    - Ensures the model is directly initialized in the device only when applicable.

This commit refines the device handling in optimum/exporters/tasks.py for the following improvements:

  - More precise device check: Instead of checking for not device.type, the condition is updated to device.type != "privateuseone". This ensures the initialization happens on the requested device only if it's not a private use device (e.g., DirectML).
  - Improved clarity: The code comments are updated to better explain the purpose of the device initialization and its benefits for large models.

  - Extends device compatibility to "privateuseone" in export_pytorch for exporting models usable on specific hardware.

This commit allows exporting PyTorch models compatible with the "privateuseone" device, potentially enabling inference on specialized hardware platforms.

This commit adds support for running PyTorch models on the DML device within the Optimum framework.

  - Dynamic DML device handling: Introduces dynamic import of torch_directml for improved maintainability.
  - Consistent device selection: Ensures consistent device selection across optimum/exporters/onnx/convert.py, optimum/exporters/tasks.py, and optimum/onnxruntime/io_binding/io_binding_helper.py.

This change allows users to leverage DML capabilities for efficient PyTorch model inference with Optimum.

This commit removes unnecessary code for handling the DML device in optimum/commands/optimum_cli.py.

  - Redundant import: The code previously imported torch_directml conditionally, which is no longer needed as DML device support is handled in other parts of the codebase.

This change simplifies the code and avoids potential conflicts.

This commit updates `setup.py` to include the following changes:

  - Introduces a new conditional section "exporters-directml" with dependencies required for exporting models for DML inference.
  - This section mirrors the existing "exporters" and "exporters-gpu" sections, adding `onnxruntime-directml` as a dependency.

This update ensures users have the necessary libraries for working with DML devices when installing Optimum with DML support.

…into feature/directml

…ames