add signalling action to console

signalling capabilities need to be added to the console so that all examples become executable. now there are a couple excluded from deployment.

in case of a state activity, offering the signal action is obvious.

but we still need to work out in which other situations we offer signalling. if that is not clear, then we could just stick with offering the signal action for all executions for which condition (execution.isActive() && "state".equals(execution.getActivity().getType()) resolves to true

re-enabling the examples in the demo deployment is considered part of this issue.