Further Summary Multiplot improvements (#8707)

* Create a specialized summary plot page for showing multi plots
* Make summary plots always show in grid of selected size.
* Allow dragging summary addresses into empty main window area
* Limit grid to 4x4 cells

ApplicationLibCode/UserInterface/RiuSummaryMultiPlotPage.h

@@ -0,0 +1,44 @@
+/////////////////////////////////////////////////////////////////////////////////
+//
+//  Copyright (C) 2022     Equinor ASA
+//
+//  ResInsight is free software: you can redistribute it and/or modify
+//  it under the terms of the GNU General Public License as published by
+//  the Free Software Foundation, either version 3 of the License, or
+//  (at your option) any later version.
+//
+//  ResInsight is distributed in the hope that it will be useful, but WITHOUT ANY
+//  WARRANTY; without even the implied warranty of MERCHANTABILITY or
+//  FITNESS FOR A PARTICULAR PURPOSE.
+//
+//  See the GNU General Public License at <http://www.gnu.org/licenses/gpl.html>
+//  for more details.
+//
+/////////////////////////////////////////////////////////////////////////////////
+#pragma once
+
+#include "RiuMultiPlotPage.h"
+
+class RimSummaryMultiPlot;
+
+#include <QList>
+#include <QPointer>
+#include <QWidget>
+
+class RiuSummaryMultiPlotPage : public RiuMultiPlotPage
+{
+    Q_OBJECT
+
+public:
+    RiuSummaryMultiPlotPage( RimSummaryMultiPlot* plotDefinition, QWidget* parent = nullptr );
+    ~RiuSummaryMultiPlotPage() override;
+
+protected:
+    void reinsertPlotWidgets() override;
+
+    void reservePlaceholders( int count );
+
+private:
+    RimSummaryMultiPlot*     m_summaryMultiPlot;
+    QList<QPointer<QWidget>> m_placeholderWidgets;
+};