Implement #104: add getObjectPath() for classes (#105)

* Implement #104: add getObjectPath() for classes

* Implement #104: changes requested in review

Co-authored-by: Christian Schneider <cschneider@radiodata.biz>

src/Object.h

@@ -101,6 +101,7 @@ namespace sdbus::internal {
         bool hasObjectManager() const override;
 
         sdbus::IConnection& getConnection() const override;
+        const std::string& getObjectPath() const override;
 
     private:
         using InterfaceName = std::string;