Provide better error message on missing @ControllerConfiguration annotation

[csviri]

Currently there is quite cryptic exception:

Exception in thread "main" java.lang.ClassCastException: class [Ljava.lang.Object; cannot be cast to class [Ljava.lang.Class; ([Ljava.lang.Object; and [Ljava.lang.Class; are in module java.base of loader 'bootstrap')
	at io.javaoperatorsdk.operator.api.config.AnnotationControllerConfiguration.getEventFilter(AnnotationControllerConfiguration.java:95)
	at io.javaoperatorsdk.operator.processing.event.source.controller.ControllerResourceEventSource.<init>(ControllerResourceEventSource.java:42)
	at io.javaoperatorsdk.operator.processing.event.EventSources.initControllerEventSource(EventSources.java:26)
	at io.javaoperatorsdk.operator.processing.event.EventSourceManager.<init>(EventSourceManager.java:44)
	at io.javaoperatorsdk.operator.processing.Controller.<init>(Controller.java:73)
	at io.javaoperatorsdk.operator.Operator.register(Operator.java:164)
	at io.javaoperatorsdk.operator.Operator.register(Operator.java:136)
	at io.javaoperatorsdk.operator.sample.presentation.Runner.main(Runner.java:12)