Analogue of .last() method

[xamgore]

I'd like to run FuturesOrdered::from_iter(...) and retrieve the result of the last element, which is Option<...>. The same function exists in std.

It can be implemented with

iter.fold(None, |_acc, x| async move { Some(x) })

But try_last would require extra checks: if there is an intermediate error, return it. If not, return the last successful Ok(...).