macOS/Windows: adding new windowState event to indicate that window was activated/deactivated

[Shchvova]

Event name: windowState
Event data: phase is either "foreground" or "background".

Runtime:addEventListener( "windowState", function(e)
	if e.phase == "foreground" then
		-- do something when activating
        elseif  e.phase == "background" then
                --- deactivate stuff not needed in background
	end
end )