Feature/appconfigurator validation migration

[mdroll]

Overall Goal

The goal is to move the validation methods from the config/ApplicationConfigurator class into domain-specific feature classes and their respective validate methods.

Directly moving them was not possible since the domain-specific feature classes are only executed at runtime.
As the validate methods are currently being implemented in the GIT abstraction feature, those methods were used as a foundation for moving validation logic into feature-specific validate methods.

The main idea is that each feature class should be able to configure and validate itself.
In the future, this approach should be extended to support not only validation but also setter methods.

Since a complete refactoring and migration would be too large for one step, the following was implemented in this PR:

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Implementation

1. A hook system that integrates into the initialization process.
2. Feature methods can now be used for self-configuration by implementing
   preConfigInit and postConfigInit.
3. If a validation involves multiple features, a central location named
   CommonFeatureConfig has been created in the config package.
   This class can be shared between several features.
   Although it extends the Feature class, it is explicitly ignored in the
   DI context and test context.

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Next Steps

With the implementation of this story, the extraction of the Registry Feature configuration will be tested.
This feature should have minimal dependencies, serving as a proof of concept for the new structure.