[test][components] Add isIon to the component traits test

test/material/components/test_componenttraits.cc

@@ -37,5 +37,6 @@ int main(int argc, char *argv[])
     static_assert(Traits::hasGasState, "Air component is reported to have no gas state?!");
     static_assert(!Traits::hasSolidState, "Air component is reported to implement a solid state?!");
     static_assert(!Traits::hasLiquidState, "Air component is reported to implement a liquid state?!");
+    static_assert(!Traits::isIon, "Air component is reported to be an ion?!");
     static_assert(std::is_same<double, Traits::Scalar>::value, "Scalar type not correctly reported!");
 }