Remove entity constructors except no-arg

- new approach is to use EntitySpec; don't include other constructors
Update Rebind*Test to use EntitySpecs
Updating more tests to use EntitySpecs
JMSBroker/destination: extract interface+impl

- Convert JMSBroker to an interface (and add rename class as Impl)
- Convert JMSDestination to interface (and add rename class as Impl)
- Same for QpidDestination, QpidTopic, QpidQueue
- Same for ActiveMQDestination, ActiveMQTopic, ActiveMQQueue