[DEVPLAT-6026] Make logging http writer SSE compatible

[Neurostep]

Description

In this PR we make the logging Response Writer wrapper SSE compatible by adding the Flush method to it.

Testing considerations

• Use in API Gateway and see if middleware works as expected with SSE enabled for GraphQL

Checklist

• Prefixed the PR title with the JIRA ticket code
• Performed simple, atomic commits with good commit messages
• Verified that the commit history is linear and commits are squashed as necessary
• Thoroughly tested the changes in development and/or staging
• Updated the README.md as necessary

Related links

• DEVPLAT-6026
• Design Document

[Copilot]

Pull Request Overview

This PR adds HTTP Flusher support to the loggingResponseWriter by implementing the Flush() method. This allows the wrapped response writer to properly support streaming responses like Server-Sent Events (SSE) or chunked transfer encoding.

Key Changes

• Implements Flush() method on loggingResponseWriter that delegates to the underlying http.ResponseWriter if it implements http.Flusher

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[Copilot]

The Flush method should include a comment documenting its purpose, similar to the WriteHeader method above it. This is especially important since it implements the http.Flusher interface and its silent failure behavior (when the underlying writer doesn't support flushing) should be documented.

[terranisu]

Looks flushed to me