🏆 Group leaderboard 📋

Maybe this is already planned. In groups it would be nice to have statistics / leaderboard over all memorizations. The current per memorization leaderboard is already nice, but to keep track of who really worked the hardest it would help when each member of the group could see, who learned / mastered how many memorization and what the average progress is, and also very nice, on what review level (this could be added to the per memorization leaderboard as well) one is, so how much time he advanced.