feat: add impl AsyncRead for ResponseDataStream

[TaQuanMinhLong]

Hi, I think ResponseDataStream is missing the implementation of AsyncRead trait, which allows us to pass the stream to a reader instead of putting the whole file in memory

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This change is 

[Copilot]

Pull Request Overview

This PR adds an AsyncRead trait implementation for ResponseDataStream to enable streaming data to readers without loading entire files into memory. This is useful for processing large S3 objects efficiently.

• Implements tokio::io::AsyncRead for ResponseDataStream under the with-tokio feature flag
• Updates the with-tokio feature dependency to include futures/alloc for the implementation

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
s3/src/request/request_trait.rs	Adds AsyncRead implementation for ResponseDataStream with proper error handling and buffer management
s3/Cargo.toml	Updates with-tokio feature to include futures/alloc dependency

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[Copilot]

The implementation doesn't check if the chunk size exceeds the buffer's remaining capacity. This could cause a panic if the chunk is larger than the available buffer space. Consider using buf.remaining() to check capacity and handle partial writes appropriately.

[Copilot]

When the stream ends (None), the implementation should signal EOF by returning 0 bytes read. The current implementation returns Ok(()) but doesn't indicate to the reader that no more data is available. Consider checking if any bytes were written to the buffer and handle EOF correctly according to AsyncRead semantics.

Suggested change

	std::task::Poll::Ready(None) => std::task::Poll::Ready(Ok(())),
	// If no bytes were written to the buffer in this poll, signal EOF by returning Ok(())
	std::task::Poll::Ready(None) => {
	// If the buffer was not filled in this poll, this signals EOF (0 bytes read)
	std::task::Poll::Ready(Ok(()))
	},

[durch]

@TaQuanMinhLong good call out, but I'll implement it a bit differently, there are some issues here, and a lack of tests, but good callout