[libinput] Add more support for pointer devices, in particular touchpads

This patch is made in preparation for the Touchpad KCM for Wayland.

Summary:
* KWin has a Libinput version requirement bump to 1.5
* new isTouchpad property to distinguish touchpads from mice
* new lmrTapButtonMap property
* new disableWhileTyping property
* new pointerAccelerationProfile property
* new defaultPointerAcceleration property
* save to config mechanism added for new propertys and pointerAcceleration
* new D-Bus interface org.kde.KWin.InputDeviceManager and method devicesSysNames
* removed unnecessary additional D-Bus service name org.kde.KWin.InputDevice
* changing acceleration in the Mouse KCM doesn't influence touchpads anymore

Reviewers: #kwin, #plasma, davidedmundson

Subscribers: plasma-devel, kwin

Tags: #kwin

Differential Revision: https://phabricator.kde.org/D3479