Add feature to duplicate tabs (#5277)

Co-authored-by: Rasmus Karlsson <rasmus.karlsson@pajlada.com>

src/widgets/splits/SplitContainer.hpp

@@ -220,6 +220,7 @@ public:
     void hideResizeHandles();
     void resetMouseStatus();
 
+    NodeDescriptor buildDescriptor() const;
     void applyFromDescriptor(const NodeDescriptor &rootNode);
 
     void popup();
@@ -237,6 +238,7 @@ protected:
     void resizeEvent(QResizeEvent *event) override;
 
 private:
+    NodeDescriptor buildDescriptorRecursively(const Node *currentNode) const;
     void applyFromDescriptorRecursively(const NodeDescriptor &rootNode,
                                         Node *baseNode);