Add half-open stream

[cowlicks]

(pulled in #5)

This lets us create a "half-open" stream. This is useful because it prevents any stream messages which have the half-open stream's id from being routed as socket messages. The javascript library does something similar.

More concretely, I use this in hyperdht. When I first send a handshake message with the stream id encoded, I create this half-open stream. I can't fully open the stream until I get a reponse which includes the remote stream id. But I may receive udx messages before I can read and process the remote stream id. These messages were causing errors.

Added a CHANGELOG.md and release.toml.
Bumped to edition 2024
Fixed all lints
cargo fmt everything

[Frando]

Thanks! I'm not working on this anymore and don't see myself coming back to datrs things, so I've moved the repo into the datrs org.