Add xf86-input-libinput support for X11 mouse backend.

Summary:
Added libinput support to X11 backend. It also adds an new option to backend
which is only available to libinput device currently.

Test Plan: Manually tested and inspect with xinput tool.

Reviewers: ngraham, #plasma, jriddell

Reviewed By: ngraham, #plasma, jriddell

Subscribers: subdiff, jriddell, apol, rkflx, plasma-devel

Tags: #plasma

Differential Revision: https://phabricator.kde.org/D8798