BEN2 (Background Erase Network) for image background removal added

[Naveen56001]

Description

This PR resolves #70 issue. Added BEN2 image background remove model to opentryon. single and batch background remove features added with refinement option as well. Included CLI integration and documentation update as well.

Type of Change

• New feature (non-breaking change that adds functionality)
• Documentation update
• Performance improvement

Component Affected

• CLI Tools
• Documentation
• Other: BEN2 Image Background Removal

Changes Made

• Added BEN2 model for Image Background Removal
• Implemented single and batch image background removal
• Provided functionality for using refine functions for enhanced background removal
• Integrated CLI commands for BEN2
• Updated README with usage examples and CLI docs
• Validated all modes locally
• Carefully and safely integrated the required minimal inference code from BEN2

Testing

• I have tested these changes locally

Checklist

• My code follows the project's style guidelines
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings

[Naveen56001]

Made changes to the PR request which follow community guidelines.

[Naveen56001]

PR checks are failing due to GitHub Actions billing / permission issue on repo workflows. Code builds fine locally.