Event subscription naming does not use fully-qualified handler type name

[flakey-bit]

The implementation of PathFactory::SubscriptionNameFor() currently uses handlerType.Name. It should use .FullName because otherwise an event subscription will get lost if there are two handlers for the same event type which happen to be named the same (but under different namespaces).

Note - this issue affects V3 too - see NimbusAPI/Nimbus#274