Source stepping and toolbar updates (#8866)

* Move layout options to separate toolbar
* Enable stepping on quantities, remove special history curve stepping for now
* Allow stepping ensembles and cases
* Add step next/prev and add new sub plot

ApplicationLibCode/ProjectDataModel/Summary/RimSummaryPlot.h

@@ -204,6 +204,8 @@ public:
 
     std::vector<RimPlotCurve*> visibleCurvesForLegend() override;
 
+    RimSummaryPlotSourceStepping* sourceStepper();
+
 public:
     // RimViewWindow overrides
     void deleteViewWidget() override;