OZG-2651 adjust naming; remove embedded user-manager

Jenkinsfile

pom.xml

user-manager/.dockerignore

user-manager/.gitignore

user-manager/.mvn/wrapper/MavenWrapperDownloader.java

user-manager/.mvn/wrapper/maven-wrapper.properties

user-manager/README.md

user-manager/mvnw

user-manager/mvnw.cmd

user-manager/pom.xml

user-manager/src/main/docker/Dockerfile.jvm

user-manager/src/main/docker/Dockerfile.legacy-jar

user-manager/src/main/docker/Dockerfile.native

user-manager/src/main/docker/Dockerfile.native-micro

...ger/src/main/java/de/itvsh/kop/user/GreetingResource.java

...-manager/src/main/resources/META-INF/resources/index.html

user-manager/src/main/resources/application.properties

...r/src/test/java/de/itvsh/kop/user/GreetingResourceIT.java

...src/test/java/de/itvsh/kop/user/GreetingResourceTest.java