libp2p-stream: open a stream with an explict connection_id

[Heap-Hop]

Description

Currently, the stream is opened randomly on connections.

It would be great to allow callers to open a stream on an explicit connection ID.

Motivation

For instance, when opening a stream, you can choose to prefer direct connections or relay connections.

Requirements

Add a method like

pub async fn open_stream_on_connection(
        &mut self,
        peer: PeerId,
        connection: ConnectionId,
        protocol: StreamProtocol,
    ) -> Result<Stream, OpenStreamError>

ConnectionId is enough because the caller can maintain a ConnectionId <-> Connection state map of its own.

Open questions

Actually, I’ve implemented one for my project (with AI):

Heap-Hop@b5c6bd0

It works fine on my project fungi.

I'm not sure it is a necessary feature for rust-libp2p.

If it’s done correctly, I’d love to open a PR.
If not, and there’s a better way to achieve the same result, please let me know.

Furthermore, it would be great if the listener side could add a method like accept_with_id that also provides the connection ID for new streams.

Are you planning to do it yourself in a pull request?

Yes