OZG-1062 refactoring for using body in command for senden postfach mail

goofy-server/pom.xml

.../main/java/de/itvsh/goofy/common/command/CommandBody.java

...java/de/itvsh/goofy/common/command/CommandBodyMapper.java

...java/de/itvsh/goofy/common/command/CommandController.java

...ain/java/de/itvsh/goofy/common/command/CreateCommand.java

...rc/main/java/de/itvsh/goofy/postfach/PostfachMessage.java

...in/java/de/itvsh/goofy/vorgang/AssignUserCommandBody.java

.../de/itvsh/goofy/common/command/CommandBodyMapperTest.java

...e/itvsh/goofy/common/command/CommandControllerITCase.java

.../de/itvsh/goofy/common/command/CommandControllerTest.java

...est/java/de/itvsh/goofy/common/command/CommandITCase.java

...ava/de/itvsh/goofy/common/command/CommandTestFactory.java

...a/de/itvsh/goofy/postfach/PostfachMessageTestFactory.java

...plates/command/createCommandWithPostfachMessage.json.tmpl

...plates/command/createCommandWithRedirectRequest.json.tmpl

...rces/jsonTemplates/command/createVorgangCommand.json.tmpl

pom.xml