Inspector: Stringify remote property values

This prevents us from asserting if the remote sends us a property made
up of an array or object.

DevTools/Inspector/RemoteObjectPropertyModel.cpp

@@ -56,7 +56,7 @@ GUI::Variant RemoteObjectPropertyModel::data(const GUI::ModelIndex& index, Role
  case Column::Name:
  return property.name;
  case Column::Value:
- return property.value;
+ return property.value.to_string();
  }
  }
  return {};