Consider exposing one-shot receiver from ByteWriter write function

[wxing1292]

Problem description

pub async fn write(&mut self, buf: &[u8]) -> Result<usize, Error>

does not expose the inner one shot channel, caller can potentially benefit from async notification if the one-shot channel is exposed (instead of calling the flush method, which takes &mut self)

Problem location
link

Suggestions for an improvement
Expose the one shot receiver (perhaps change to broadcast receiver?)