Add a simple test for keyboard events generation.

Add a simple test for keyboard events generation.

Check that the events generated by wxUIActionSimulator result in the same
wxKeyEvents being generated under all platforms. This is not the same as
checking the event generation for the actual keys pressed by the user as there
are some small differences between the two but better than nothing.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@65519 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775