WIP: support native event in qtestlib

Only finished key events on cocoa and windows now.

macnativeevents was moved to nativeevents

todo:
* current testlib depends on gui and platform plugins
* key events on other platforms, like xcb
* mouse events

Task-number: QTBUG-35968
Change-Id: Ie05e590ebdcc4a939d1e2a8e5717c6ba5d074e08