Composite tasks do not notify parent composites

WhenAllTask and WhenAnyTask mark themselves complete, but do not notify their parent composite.

This means the following orchestration does not resume when all activities complete:

all_task = task.when_all(activity_tasks)
winner = yield task.when_any([cancel_task, all_task])

A current workaround is to wait for each leaf task with repeated when_any calls. The workaround preserves cancellation, but Durable Task Scheduler no longer shows the standard Fan-out group.

Could composite completion propagate to the parent in the same way that CompletableTask.complete() does?

A regression test can compose when_any([cancel, when_all([a, b])]), complete a and b, and verify that the outer task completes with the inner when_all task.

Inizia leggendo WhenAllTask e WhenAnyTask, quindi confronta il loro comportamento al completamento con CompletableTask.complete(). Aggiungi il test di regressione descritto nell’issue per when_any([cancel, when_all([a, b])]); «done» significa che il completamento di a e b fa sì che il task esterno venga completato con il task when_all interno.