Support distinct if multiple ES for same type for getSecondaryResources()

[csviri]

If there are multiple event sources for the same Kind, Context.getSecondaryResources returns a stream of the resources. If there are multiple event sources that return an overlap, thus the same resources, we could provide a filter to make sure the resources are distinct. Now we can also compare the versions and return the one with the higher resource version.

Maybe we could also just provide a special filter, like:
see also: https://www.baeldung.com/java-streams-distinct-by

However we probably don't want to apply this by default because of performance reasons.