Consider offering `try_next() -> Result<Option<T>>` for our stream-like things

Our stream-like things all have a `next()` (or maybe `poll()`) method which return an `Option>`.

So often example code looks like:

```rs
let mut stream = ...;
while let Some(item) = stream.next().await.transpose()? {
println!("item={item:?}");
}
```

To slightly improve application ergonomics, we could consider offering a `try_next()` for our streams as a shorthand for omitting the `transpose()` (akin to `futures::TryStreamExt`)

```rs
let mut stream = ...;
while let Some(item) = stream.try_next().await? {
println!("item={item:?}");
}
```