OZG-4949 Refactoring setting classes

...ud/admin/common/errorhandling/ValidationMessageCodes.java

...d/admin/configurationparameter/DataRestConfiguration.java

...e/ozgcloud/admin/settings/AdminEnvironmentRepository.java

...a/de/ozgcloud/admin/settings/ConfigurationProperties.java

...n/java/de/ozgcloud/admin/settings/PropertyRepository.java

src/main/java/de/ozgcloud/admin/settings/Settings.java

src/main/java/de/ozgcloud/admin/settings/SettingsBody.java

...in/java/de/ozgcloud/admin/settings/SettingsConstants.java

...n/java/de/ozgcloud/admin/settings/SettingsRepository.java

...in/java/de/ozgcloud/admin/settings/postfach/Absender.java

...in/java/de/ozgcloud/admin/settings/postfach/Postfach.java

.../ozgcloud/admin/security/SecurityConfigurationITCase.java

...va/de/ozgcloud/admin/settings/AdminEnvironmentITCase.java

...loud/admin/settings/AdminEnvironmentRepositoryITCase.java

...gcloud/admin/settings/AdminEnvironmentRepositoryTest.java

...ud/admin/settings/ConfigurationPropertiesTestFactory.java

src/test/java/de/ozgcloud/admin/settings/SettingsITCase.java

.../java/de/ozgcloud/admin/settings/SettingsTestFactory.java

...ozgcloud/admin/settings/postfach/AbsenderTestFactory.java

...a/de/ozgcloud/admin/settings/postfach/PostfachITCase.java