Simpler way to trigger projections

[dgafka]

This PR, introduces new way of triggering projections.

Old solution

Before each Projection's Event Handler was connected directly to Event Bus. As we did not want to trigger the Event Handler directly, as we needed to pull the events from Event Stream (Stream Source), it required bit of complex solution of intercepting the Event Handler checking what kind of execution it's and based on that execute projection instead or skip if that was polling projection.

New solution

New solution reorganizes the flow, so it does not require conditional flow changes.
Whenever we register Event Handler that is connected to Stream Source, it will not connect it to the Event Bus.

Polling

If polling consumer was chosen for the projection. It will register polling consumer that will continuesly pull the stream from database. No extra configuration needed.

Synchronous Event-Driven

If synchronous event driven was chosen, we connect the Projection (instead of Event Handler) to the Event Bus.

Asynchronous Event-Driven

If asynchronous event driven was chosen, we set up Projection as asynchronous after connecting it to the Event Bus