Add nnUNet cascade support and MONAI Label integration

[SimoneBendazzoli93]

Summary

Add support for nnUNet cascade models within the MONet Bundle, and include integration with MONAI Label to enable interactive annotation workflows.

Motivation

• Enhance the MONet Bundle by supporting advanced nnUNet cascade models, which have shown improved performance on complex medical segmentation tasks.
• Enable seamless usage of MONet models with MONAI Label for user-driven annotation and evaluation workflows.

Acceptance Criteria

• MONet Bundle can be configured to use nnUNet cascade models.
• MONAI Label integration supports nnUNet cascade inference within MONet Bundle.
• Documentation is updated with usage instructions for cascade support and MONAI Label configuration.
• Example config and/or demo is provided for reference.

Additional Context

• nnUNet Cascade Paper
• Refer to MONAI Label's documentation for integration patterns.

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This feature is important for extending MONet's model compatibility and user flexibility for clinical and research workflows.