#14192 Python: Update discrete property color legend in place instead of delete/create

Address review feedback on #14199: deleting and recreating the legend left
views bound to the old legend pointing at a deleted object. Add
RimColorLegendCollection::updateColorLegend and a matching UpdateColorLegend
scriptable method that mutate the existing custom legend (name and items) so
referring views keep their binding and are notified once. A new legend is only
created when none is registered for the result or the registered legend is a
standard legend.

set_discrete_property_category_names now performs a single atomic call instead
of delete + create + per-item appends. The empty-dict removal path still uses
DeleteColorLegend.

ApplicationLibCode/ProjectDataModel/RimColorLegendCollection.h

@@ -22,6 +22,8 @@
 #include "cafPdmField.h"
 #include "cafPdmObject.h"
 
+#include "cvfColor3.h"
+
 class RimCase;
 class RimColorLegend;
 class RimColorLegendItem;
@@ -50,6 +52,12 @@ public:
     void deleteCustomColorLegends();
 
     RimColorLegend* createColorLegend( const QString& colorLegendName, const std::map<int, QString>& valuesAndNames );
+    RimColorLegend* updateColorLegend( const RimCase*                   rimCase,
+                                       const QString&                   resultName,
+                                       const QString&                   colorLegendName,
+                                       const std::vector<int>&          categoryValues,
+                                       const std::vector<QString>&      categoryNames,
+                                       const std::vector<cvf::Color3f>& colors );
     void            createColorLegendFromFormationNames( RimFormationNames* rimFormationNames );
     void            deleteColorLegend( const RimCase* rimCase, const QString& resultName );
     void            setDefaultColorLegendForResult( const RimCase* rimCase, const QString& resultName, RimColorLegend* colorLegend );