🔨 Added Tests for POT and NNCF Compression Types

[sky0walker99]

📝 Description

-This PR addresses the missing tests for the POT (Post-Training Optimization Tool) and NNCF (Neural Network Compression Framework) features in Engine.export. This PR adds unit tests to verify the export functionality with these compression types.

• Ensures compression_type is used only with OPENVINO export type, raising an error if violated in Engine.export

• Added tests in test_cli to cover all compression type combinations.

• attributes POT (Post-Training Optimization) and NNCF (Neural Network Compression Framework) to the CompressionType

• 🛠️ Fixes [Task]: Add unit tests for Engine.export #2273

✨ Changes

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• 🐞 Bug fix (non-breaking change which fixes an issue)
• 🔨 Refactor (non-breaking change which refactors the code base)
• 🚀 New feature (non-breaking change which adds functionality)
• 💥 Breaking change (fix or feature that would cause existing functionality to not work as expected)
• 📚 Documentation update
• 🔒 Security update

✅ Checklist

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• 📋 I have summarized my changes in the CHANGELOG and followed the guidelines for my type of change (skip for minor changes, documentation updates, and test enhancements).
• 📚 I have made the necessary updates to the documentation (if applicable).
• 🧪 I have written tests that support my changes and prove that my fix is effective or my feature works (if applicable).

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[samet-akcay]

@ashwinvaidya17, will you be able to review this?

[ashwinvaidya17]

Thanks for the PR, I've added a few comments