I don't really see a need for this as you can manage your pages of notifications here (as others have mentioned):
https://forums.d2jsp.org/track.php?a=30Furthermore, you can already adjust which notifications are coming in when you edit your tracked forums/topics.
If you have an abundance of notifications to the point where you need to filter them out to find ** time sensitive/important ** notifications then maybe you should reduce the amount of notifications you get from other means.
In my opinion, less is more, and in this case I don't really think being able to filter notifications is necessary lol