patch open function to convert crlf to lf

[howieleung]

Description

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• The pull request does not introduce [breaking changes]
• CHANGELOG is updated for new features, bug fixes or other significant changes.
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[Copilot]

Pull request overview

This PR implements a runtime solution for handling CRLF to LF line ending conversions in test files, replacing the previous .gitattributes-based approach. The change ensures consistent binary representation of test assets across Windows and Linux platforms during test execution.

Key Changes:

• Adds a patched open() function that automatically converts CRLF to LF for text files opened in binary read mode
• Removes .gitattributes file that previously enforced LF line endings at the git level
• Updates test assets tag to reflect the new approach

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
sdk/ai/azure-ai-projects/tests/samples/test_samples.py	Implements ConvertedFileWrapper class and _patched_open() method to handle CRLF-to-LF conversion at runtime
sdk/ai/azure-ai-projects/samples/agents/assets/.gitattributes	Removes git-level line ending enforcement for test assets
sdk/ai/azure-ai-projects/assets.json	Updates assets repository tag