Python: Added AzureAI sample for downloading code interpreter generated files

[giles17]

Motivation and Context

Users working with code interpreter could see file IDs in responses but had no guidance on how to actually download the generated files. The existing azure_ai_with_code_interpreter_file_generation.py sample only showed file ID extraction without demonstrating the download process.

This PR adds a new sample demonstrating how to download files generated by Azure AI's code interpreter tool in both streaming and non-streaming scenarios.

Closes #3143

Description

Contribution Checklist

• The code builds clean without any errors or warnings
• The PR follows the Contribution Guidelines
• All unit tests pass, and I have added new tests where possible
• Is this a breaking change? If yes, add "[BREAKING]" prefix to the title of the PR.

[Copilot]

Pull request overview

This PR adds a new sample demonstrating how to download files generated by Azure AI's code interpreter tool. It also includes a minor fix to improve import consistency in an existing sample.

Changes:

• Added new sample azure_ai_with_code_interpreter_file_download.py showing how to download files from code interpreter using the OpenAI containers API in both streaming and non-streaming scenarios
• Fixed import statement in azure_ai_with_code_interpreter_file_generation.py to use the public API export of AgentRunResponseUpdate

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 4 comments.

File	Description
python/samples/getting_started/agents/azure_ai/azure_ai_with_code_interpreter_file_generation.py	Moved AgentRunResponseUpdate import from private _agents module to public API export
python/samples/getting_started/agents/azure_ai/azure_ai_with_code_interpreter_file_download.py	New sample demonstrating file download from code interpreter with both streaming and non-streaming approaches