The window operators should indicate if the returned Flux for each window is safe to subscribe to multiple times.

Documentation Issue

I had a data processing pipeline that I introduced batching to, using the window operator. In this pipeline, it will retry a batch if it faces a transient error. When batching was added, and it retried, I saw a failure of `IllegalStateException: UnicastP

For debug purposes, it would be nice to add a mode to Mutiny which attaches stack traces to exceptions, to record where we created the Uni, rather than when it failed, which often doesn't have the right stack trace.

In the past, I've used this extensively:

    private static <V> CompletionStage<V> attachStackTrace(CompletionStage<V> cs) {
        Throwable exception = new RxExcep