Update GitHub client to improve failure handling

[srnagar]

This pull request improves the reliability and maintainability of the GithubClient class by introducing a generic HTTP request retry mechanism with exponential backoff and refactoring existing methods to use this new logic. The changes also enhance code documentation for better clarity.

Key improvements:

Resilience and Reliability:

• Added a new executeWithRetry method to GithubClient that wraps HTTP requests with retry logic, including exponential backoff and jitter, to handle transient errors more gracefully. This method also logs telemetry events on failure.

Refactoring and Code Simplification:

• Refactored getLatestAzureMcpRelease and downloadToFile methods to use the new executeWithRetry method, reducing code duplication and improving error handling.

Documentation and Readability:

• Added detailed class-level and method-level Javadoc comments to GithubClient, making the purpose and usage of the class and its methods clearer for future maintainers. [1] [2]