Ability to set scroll speed in system settings of Linux desktop environments

In order to be able to set scroll speed via the system settings of different Linux desktop environments there is needed some way of handling this (see the discussion on https://gitlab.freedesktop.org/libinput/libinput/issues/185 for reference). Thus I am creating this issue, so the relevant parties can try to figure out a way how to achieve this.

Also see https://gitlab.gnome.org/GNOME/gnome-shell/issues/950

PS: I just chose some componenty which might fit, but probably there is a better one which I was not aware of.