Add possibility to register Subscriber before the Publisher of a particular EventType

Currently new EventType is created at the moment when Publisher is being registered. This means that Subscriber for that particular EventType can register only after the successful registration of the Publisher. Such behavior leads to failures when modules register in mod-pubsub in the wrong order.

To allow Subscribers to register before the Publishers, new "temporary" eventType should be created and replaced with the complete EventDescriptor at the moment when Publisher is being registered.

Go through MessagingDescriptor.json files and delete all the fake declarations of Publishers that were added as a workaround of this issue.

Steps

• Pub-Sub should check is EventType exist during Subscriber creation
• If there is no eventType - create a temporary event and register Subscriber
• Create topic and consumer
• When someone register Publisher with EventType == tempEventType - replace Subscriber with real EventType
• Add temp flag
• Publisher rewrite EventType
• Add tests