Feature Request: Implement CID allowlist HTTP Middleware

I'm reaching out to discuss an idea I have for enhancing security and access control in the Rainbow IPFS Gateway. I'd like to gauge interest and gather feedback before deciding on implementation.

**My Idea:** Implementing CID allowlist HTTP Middleware

The goal of this feature would be to prevent flooding self-hosted instances with requests or compromised CIDs by restricting access to certain resources based on an allowlist of allowed CIDs. This would reduce the risk of Distributed Denial-of-Service (DDoS) attacks, floods of requests, and unauthorized access attempts.

Before deciding on implementation, I'd like to get your thoughts on the following:

- Is my idea aligned with the project's goals and values?
- Would this feature significantly impact performance or scalability?

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*Assuming interest in implementing this feature, here are some potential ways it could be done:*

To implement CID allowlist Middleware, we would need to add a middleware layer that intercepts incoming HTTP requests, extracts the CID from the URL path, and checks it against a predefined allowlist.

I'd be happy to contribute to this feature if you're interested. Please let me know if this is something that could be explored further, or if there are any concerns or issues with my idea.