RFE: Migrate from distributor sidecar to library

[markuslackner]

Problem statement.
Add the moment the distributor image is used for keptn event communication. There are some downsides to this approach:

• no direct access to nats features
• sidecar

Describe the solution you'd like
The new approach using the library should be used if possible! The service also to be executable in the customers environment (remote execution plane) for on premise git provider installations.