Fixed missing name for done notifications

[PyvesB]

This is a proposed fix for an issue faced by several users, namely "done" notifications containing an empty name fields when using specific vendors. See issues #351, #538, #789 and others for more information.

The idea is in essence quite simple: if the name is no longer present in the notify context (probably due to the second on_publish event mentioned by some issues), try to get it from the live context of the stream that is about to close.

I am aware that this may not necessarily be the ideal workaround, but it has proven very useful in our use cases and has given good results on our production systems. I am happy to hear about any other ideas or feedback. 👍