use changed gschema settings for scroll button
This MR uses the changed gschema from gsettings-desktop-schemas!72 and exposes On-Button scrolling functionality from libinput (https://wayland.freedesktop.org/libinput/doc/latest/scrolling.html) for mice. This was tested on a NixOS system already and has the required functionality (set the setting by hand using dconf-editor).
Edited by Eli Kogan-Wang