experiments: quote parameters for ns3 end-to-end framework by default

This avoids issues for parameter strings containing characters that are
treated specially while parsing the arguments, e.g. whitespace.

experiments/simbricks/orchestration/e2e_components.py

@@ -87,7 +87,7 @@ class E2EBase(ABC):
             child.ns3_config() for child in self.components
         ])
 
-        return f"--{self.category}={config} {child_configs}"
+        return f"--{self.category}=\"{config}\" {child_configs}"
 
     @abstractmethod
     def add_component(self, component: E2EComponent) -> None: