Separate "Around Camera" from Positional Duplicate Setting

Currently, when choosing "around camera," stroke instances are spawned basically "inside sphere" where the sphere is centred around the camera. But for things like rain this means some strokes can end higher than the camera position and so on, because it doesn't care where they begin and end really.

If we could have "On Plane" positional duplicates and "Around Camera," the plane would be centred at the camera, but the duplicates would be in an "On Plane" pattern and so would always reach below the camera position. Things like that.