This is a concrete role that implements transitions, has_transition and
has_transitions as required by Class::Workflow::State, and adds
add_transitions, remove_transitions and clear_transitions as well.
Transition storage is implemented internally with Set::Object.
Unlike Class::Workflow::State::TransitionHash this role does not require
transitions to respond to the name method, but as a consequence you must
refer to the transitions by value.
Note that you may construct like this:
transitions => \@transitions,
and the transition set will be coerced from that array reference.