Merge changes from topic "preparation_fork_clatd_from_system_server"

* changes:
  [CLATJ#24] ClatCoordinatorTest: add basic unit tests
  [CLATJ#23] Close the file descriptor manually
  [CLATJ#22] ClatCoordinator: stop clatd
  [CLATJ#21] ClatCoordinator: start clatd