Implements KeyboardEventCheckTest for libinput haltests

Implements KeyboardEventCheckTest for libinput haltests

It's same way of checking MouseEventCheckTest.
For test, get lists of libinput devices and check validation of created keyboard event.
It generates libinput keyboard event and saves sequencely. For example, key down, up, key down up.
It checkes devices capability which is keyboard, and checkes matching of events. If one of them checked successfully same events as created events, other keyboard devices can be skipped.

Change-Id: I8d20d9c324331c759bcce8a14096819b681e36ff