Updated env vars and added user service

docker-compose.yml

...service/src/main/java/at/tuwien/config/GatewayConfig.java

.../entities/src/main/java/at/tuwien/entities/user/User.java

fda-ui/.env.example

fda-ui/components/dialogs/Persist.vue

fda-ui/config.js

fda-ui/nuxt.config.js

...es/container/_container_id/database/_database_id/info.vue

...ontainer/_container_id/database/_database_id/settings.vue

fda-user-service/.gitignore

fda-user-service/.mvn/wrapper/MavenWrapperDownloader.java

fda-user-service/.mvn/wrapper/maven-wrapper.jar

fda-user-service/.mvn/wrapper/maven-wrapper.properties

fda-user-service/Dockerfile

fda-user-service/mvnw

fda-user-service/mvnw.cmd

fda-user-service/pom.xml

fda-user-service/report/pom.xml

fda-user-service/rest-service/pom.xml

...ce/src/main/java/at/tuwien/FdaUserServiceApplication.java