[partition] Shuffle Config and ViewStep to top

Modules nearly always have a Config and either a Job or ViewStep
as their "top level" components. Everything else is implementation-
detail. The *partition* module was unusual in that those two
"top level" components were tucked away in subdirectories.

Shuffle them to the top: this makes it more clear that these
two files are there to coordinate the module.

src/modules/partition/PartitionViewStep.h

@@ -0,0 +1,88 @@
+/* === This file is part of Calamares - <https://calamares.io> ===
+ *
+ *   SPDX-FileCopyrightText: 2014 Aurélien Gâteau <agateau@kde.org>
+ *   SPDX-FileCopyrightText: 2014-2016 Teo Mrnjavac <teo@kde.org>
+ *   SPDX-FileCopyrightText: 2017 Adriaan de Groot <groot@kde.org>
+ *   SPDX-License-Identifier: GPL-3.0-or-later
+ *
+ *   Calamares is Free Software: see the License-Identifier above.
+ *
+ */
+
+#ifndef PARTITIONVIEWSTEP_H
+#define PARTITIONVIEWSTEP_H
+
+#include "utils/PluginFactory.h"
+#include "viewpages/ViewStep.h"
+
+#include "DllMacro.h"
+
+#include <QObject>
+#include <QSet>
+
+class ChoicePage;
+class Config;
+class PartitionPage;
+class PartitionCoreModule;
+class QStackedWidget;
+class WaitingWidget;
+
+template < typename T >
+class QFutureWatcher;
+
+/**
+ * The starting point of the module. Instantiates PartitionCoreModule,
+ * ChoicePage and PartitionPage, then connects them.
+ */
+class PLUGINDLLEXPORT PartitionViewStep : public Calamares::ViewStep
+{
+    Q_OBJECT
+
+public:
+    explicit PartitionViewStep( QObject* parent = nullptr );
+    ~PartitionViewStep() override;
+
+    QString prettyName() const override;
+    QWidget* createSummaryWidget() const override;
+
+    QWidget* widget() override;
+
+    void next() override;
+    void back() override;
+
+    bool isNextEnabled() const override;
+    bool isBackEnabled() const override;
+
+    bool isAtBeginning() const override;
+    bool isAtEnd() const override;
+
+    void onActivate() override;
+    void onLeave() override;
+
+    void setConfigurationMap( const QVariantMap& configurationMap ) override;
+
+    Calamares::JobList jobs() const override;
+
+    Calamares::RequirementsList checkRequirements() override;
+
+private:
+    void initPartitionCoreModule();
+    void continueLoading();
+
+    /// "slot" for changes to next-status from the KPMCore and ChoicePage
+    void nextPossiblyChanged( bool );
+
+    Config* m_config;
+
+    PartitionCoreModule* m_core;
+    QStackedWidget* m_widget;
+    ChoicePage* m_choicePage;
+    PartitionPage* m_manualPartitionPage;
+
+    WaitingWidget* m_waitingWidget;
+    QFutureWatcher< void >* m_future;
+};
+
+CALAMARES_PLUGIN_FACTORY_DECLARATION( PartitionViewStepFactory )
+
+#endif  // PARTITIONVIEWSTEP_H