[partition] Use KPM manager in partitioning jobs

- This gives all the partition-changing jobs an easy way to
   manage the lifetime of the privileged helper.

src/modules/partition/jobs/PartitionJob.h

@@ -1,6 +1,7 @@
 /* === This file is part of Calamares - <https://github.com/calamares> ===
  *
  *   Copyright 2014, Aurélien Gâteau <agateau@kde.org>
+ *   Copyright 2019, Adriaan de Groot <groot@kde.org>
  *
  *   Calamares is free software: you can redistribute it and/or modify
  *   it under the terms of the GNU General Public License as published by
@@ -19,12 +20,13 @@
 #ifndef PARTITIONJOB_H
 #define PARTITIONJOB_H
 
-#include <Job.h>
+#include "Job.h"
+#include "partition/KPMManager.h"
 
 class Partition;
 
 /**
- * Base class for jobs which affect a partition.
+ * Base class for jobs which affect a partition and which use KPMCore.
  */
 class PartitionJob : public Calamares::Job
 {
@@ -46,6 +48,7 @@ public slots:
     void iprogress( int percent );
 
 protected:
+    CalamaresUtils::Partition::KPMManager m_kpmcore;
     Partition* m_partition;
 };