Add check for overriding event annotations

[LeStegii]

If a method is annotated with an event annotation such as @OnInit and is overriding a method from a super class which is also annotated with an event annotation, the method in the class will be called twice due to how java handles overwriting methods.

Therefore, overriding an event method shouldn't be allowed and will result in the following error:
Method 'method()' annotated with an event annotation in class 'de.uniks.ludo.controller.SetupController' overrides event method in class 'de.uniks.ludo.controller.BaseController'. [FFX1013]

• Check method overrides in reflection sidecar
• Check method overrides in processor sidecar

This PR refactors the processing classes by adding a helper class which doesn't contain framework specific code but methods for streaming different elements

Fixes #86

[LeStegii]

Everything should now work as expected. However, when there is a chain of inheriented classes like Parent.class -> Sub.class -> SubSub.class which override each others methods, some error messages can be duplicated.

While this doesn't affect the process itself, it could be harder to read the error in certain conditions.
For SubSub.class, this happens because the method not only overrides the method of its direct parent, but also the parent's parent.