Add configuration for kinetic scroll on Linux

[clemisch]

Problem description

A recent ST4 update introduced kinetic scroll on Linux.

1. There seems to be no setting to deactivate it. I personally don't like it, and while that is subjective it would be nice to having the option to turn it off.
2. It seems to break the "scroll_speed" setting. Its value has no effect at all now, if scrolling with a touchpad.

Fyi, I dislike kinetic scroll because it often leads to small jumps when lifting my fingers off the touchpad (T480s). Even if I completely stop the scrolling motion and only then lift my fingers, the view almost always shifts by ~1-3 lines. I think multiple applications have that problem but somehow I notice it most in ST4.

FWIW I'm using Fedora 40 with Gnome 46.4 on Wayland.

Preferred solution

1. Add setting to deactivate kinetic scroll on Linux
2. Make scroll_speed have an effect even if kinetic scroll is enabled

Alternatives

Deactivating kinetic scroll could be implemented via "scroll_speed": 0.0. Initially I expected this to do it, but no.

Additional Information

No response