Kinetic scrolling support for touchpads (Linux?)

### Is there an existing issue for this? - [x] I have searched the existing issues ### Problem I put Linux in the title, but it may affect other OSes. I only am able to test on Linux. Normally when scrolling with a touchpad, programs have a momentum effect, so if you move your fingers quickly and let go, it keeps scrolling for a bit until it naturally slows down. At least on Wayland, it seems programs have to implement this themselves. So on Zathura, when I take my fingers off the touchpad, it immediately stops scrolling. It also feels very sluggish to try and scroll quickly through a page since the momentum can't add up with multiple quick swipes. ### Expected behavior Take a look at what other programs such as Firefox, Chromium, scrolled menus in GTK3/GTK4, etc behave when scrolled with a trackpad. When you let go, the momentum keeps the scrolling for a little bit, and if you swipe quickly multiple times in a row, it speeds up.