feat: UI elements for key combinations

modules/terrain_editor/edit_history.h

@@ -20,6 +20,7 @@ public:
 	void push_action(Callable do_action, Callable undo_action);
 	void undo();
 	void redo();
+	void clear_history();
 
 private:
 	size_t undo_count{ 0 };