Add a "NodeQueue: Not in a queue" views filter

As per discussion on IRC, it'd be nice to have a views filter for "nodes that don't belong to a certain queue" and/or "nodes that don't belong to any queues". Unfortunately, the UI is a little wonky since a) 'operator' is required, and b) the existing filters for "NodeQueue: Queue" can't work like this, since we need a special handler. I'm not thrilled by this, and perhaps it'd be possible to make this work better in the future, but meanwhile, it works, and solves my problem. I'm happy to make improvements if anyone has concrete suggestions.

Also, this patch includes a fix to nodequeue_handler_queuelist(). It wasn't handling '#all_ok' properly, since it was looking in the wrong place (at least via my testing). Not sure if this is the right fix, if we should move this into a different issue, or what.