OZG-4814 Makes administration to a spring cloud config server on an mongodb

pom.xml

...ain/java/de/ozgcloud/admin/AdministrationApplication.java

...e/ozgcloud/admin/environment/EnableMongoConfigServer.java

...zgcloud/admin/environment/MongoEnvironmentRepository.java

.../environment/MongoEnvironmentRepositoryConfiguration.java

...va/de/ozgcloud/admin/environment/MongoPropertySource.java

src/main/resources/application.yml

.../de/ozgcloud/admin/environment/MongoConfigServerTest.java

...oud/admin/environment/MongoEnvironmentRepositoryTest.java