[users] Move job-creation to Config

- this makes Config entirely stand-alone: it has all the business
  logic and can be hooked up to alternate UIs or used from
  other view steps or jobs

src/modules/users/UsersViewStep.h

@@ -57,7 +57,7 @@ public:
 
 private:
     UsersPage* m_widget;
-    QList< Calamares::job_ptr > m_jobs;
+    Calamares::JobList m_jobs;
 
     Config* m_config;
 };