Add support to (Left|Right) Pop N elements using `ReactiveListOperations`

[ericsouza]

Hey, thanks for this amazing library!

I was converting my blocking ListOperations that uses a leftPop(key, count) to a reactive version. But it seems that the ReactiveListOperations does not have an option to pop N elements. Is there any reason for that?

[mp911de]

Seems like an oversight on our end. leftPop was introduced with version 2.6.0, there is even a lPop method on the list connection commands interface.