[partition] Start sanitizing the Jobs on a Device

- having a struct with an obtuse API for adding jobs-that-need-to-happen-
  to-this-device is just not good for maintainability.
- break the build by making things private.

src/modules/partition/core/PartitionCoreModule.h

@@ -255,13 +255,17 @@ private:
         QScopedPointer< Device > device;
         QScopedPointer< PartitionModel > partitionModel;
         const QScopedPointer< Device > immutableDevice;
-        Calamares::JobList jobs;
 
         // To check if LVM VGs are deactivated
         bool isAvailable;
 
         void forgetChanges();
         bool isDirty() const;
+
+        const Calamares::JobList& jobs() const { return m_jobs; }
+
+    private:
+        Calamares::JobList m_jobs;
     };
     QList< DeviceInfo* > m_deviceInfos;
     QList< Partition* > m_efiSystemPartitions;