[autotests/integration] Add a global shortcuts test

New test case to verify that global shortcut triggering works correctly.
First test case is to verify that consumed modifiers do not break the
shortcut. E.g. a shortcut registered for % should trigger on Shift+5 on
us layout. For that the modifier needs to be consumed, otherwise it's
Shift+% and doesn't trigger. As the test shows this is currently the
case.