Exposed via new configuration option this enables 3 and 4 finger
dragging on touchpads. When enabled a 3/4 finger swipe
gesture is actually a button down + motion + button up sequence.
If tapping is disabled the drag starts immediately, if tapping is
enabled the drag starts after the tap timeout/motion so we can distinguish
between a tap and a drag.
When fingers are released:
- if two fingers remain -> keep dragging
- if one finger remains -> release drag, switch to pointer motion
When 3/4 fingers are set down immediately after releasing all fingers
the drag continues, similar to the tap drag lock feature. This drag lock
is not currently configurable.
This matches the macos behavior for the same feature.
Part-of: <https://gitlab.freedesktop.org/libinput/libinput/-/merge_requests/1042>
