Add REST API fallback for PR files collection

[Xiaoha-cloud]

Description

• This PR implements a fallback mechanism to collect pull request files using GitHub's REST API when the GraphQL query fails. The changes address the issue where some PR files are not accessible via GraphQL but can be retrieved through the REST API.

This PR fixes #2875

Notes for Reviewers

1. augur/tasks/github/pull_requests/files_model/core.py

   • Added REST API fallback mechanism when GraphQL returns None
   • Implemented error handling for cases where PR doesn't exist
   • Added logging for better debugging
   • Modified the file collection logic to try REST API when GraphQL fails
   • This directly addresses the issue by providing an alternative data collection method

2. augur/tasks/github/util/github_api_errors.py (New)

   • Added base exception class GitHubAPIError for GitHub API errors
   • Added RateLimitError for handling rate limit issues
   • Added AuthenticationError for authentication failures
   • This provides a consistent error handling structure across the codebase

3. augur/tasks/github/util/github_graphql_data_access.py (Modified)

   • Enhanced error handling for GraphQL API requests
   • Improved handling of None responses
   • Added better logging for API failures
   • This ensures robust GraphQL communication and error recovery

4. augur/tasks/github/util/retry.py (New)

   • Added error handling classes for API failures
   • Implemented retry mechanism with exponential backoff
   • Added rate limit handling
   • This file is necessary to handle API failures gracefully and ensure reliable data collection

Implementation Details

• When GraphQL returns None (as in the example with PR Pipermail SQL Date Column #121 in Picovoice/porcupine), the system now automatically falls back to the REST API
• For non-existent PRs (like PR Calculating the Truck-Factor of git Applications #27 in automatic1111/stable-diffusion-webui), the system handles the error gracefully
• The implementation maintains backward compatibility while adding the new fallback mechanism
• Error handling is now more robust with dedicated exception classes
• Rate limiting is handled more gracefully with proper retry mechanisms

Signed commits

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