[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