Add Timer Function to delete Cloudflare R2 snippets

[paul-fresquet]

This pull request introduces support for cleaning up expired Cloudflare R2 storage snippets in addition to the existing Azure Blob Storage cleanup functionality. It refactors and renames Azure-related code for clarity and consistency, and adds comprehensive tests for both storage providers.

Cloudflare R2 cleanup feature:

• Added new Cloudflare R2 cleanup function CleanupCloudflareR2SnippetsFunction and corresponding request/handler classes, enabling scheduled deletion of expired objects from R2 buckets. [1] [2] [3] [4]
• Implemented ICloudflareR2Service interface and CloudflareR2Service class to abstract Cloudflare R2 S3 API operations (ListObjectsAsync, DeleteObjectAsync). [1] [2]

Azure Blob Storage cleanup refactor:

• Renamed Azure Blob Storage cleanup function and request/handler classes for clarity (CleanupBlobStorageSnippetsFunction → CleanupAzureBlobStorageSnippetsFunction, CleanupBlobStorageSnippetsRequest → CleanupAzureBlobStorageSnippetsRequest). [1] [2] [3] [4] [5] [6]

Testing improvements:

• Added unit tests for the new Cloudflare R2 cleanup function and handler, covering deletion logic, retention policy, and error handling. [1] [2]
• Updated Azure Blob Storage cleanup handler tests to use the new request class. [1] [2] [3] [4]