refactor: Add str() method to BaseTagDecorator (#2020)

Fix: https://github.com/XRPLF/clio/issues/2008

src/util/Taggable.hpp

@@ -96,6 +96,19 @@ public:
         decorator.decorate(os);
         return os;
     }
+
+    /**
+     * @brief Gets the string representation of the tag.
+     *
+     * @return The string representation of the tag
+     */
+    std::string
+    toString() const
+    {
+        std::ostringstream oss;
+        decorate(oss);
+        return std::move(oss).str();
+    }
 };
 
 /**