Only include CloudEvents transformer service pattern if camel-quarkus-cloudevents is on the classpath

[jamesnetherton]

At the moment there is a service inclusion pattern set in the CQ core like META-INF/services/org/apache/camel/transformer/*.

This means that all transformers provided by Camel components will get discovered. We should exclude any CloudEvents transformers by default unless camel-quarkus-cloudevents is on the classpath.

Otherwise we have to keep on explicitly adding camel-cloudevents in a bunch of places, where it should be optional.