CMake: Improve delegates for CMake configuration

Change-Id: Ib1d2bfca1b2faafd36c53f24c6649e73ee0af190
Reviewed-by: Tim Jenssen <tim.jenssen@qt.io>

src/plugins/cmakeprojectmanager/configmodel.h

@@ -38,9 +38,7 @@ class ConfigModel : public Utils::TreeModel<>
 
 public:
     enum Roles {
-        ItemTypeRole = Qt::UserRole,
-        ItemValuesRole,
-        ItemIsAdvancedRole
+        ItemIsAdvancedRole = Qt::UserRole,
     };
 
     class DataItem {
@@ -78,6 +76,8 @@ public:
     bool canForceToString(const QModelIndex &idx) const;
     void forceToString(const QModelIndex &idx);
 
+    static DataItem dataItemFromIndex(const QModelIndex &idx);
+
     QList<DataItem> configurationChanges() const;
 
 private: