feat: a convenient wrapper for buf ring

[Berrysoft]

This is an implementation for a raw buffer ring that doesn't own the buffers, based on liburing impl. It will be convenient for developers to implement their own safe buffer ring.

[quininer]

Sorry, due to work, I don't have energy to maintain more API at the moment. You can maintain it in your own project.

[SUPERCILEX]

There's also https://github.com/tokio-rs/io-uring/pull/256