message: add reflection into test_install
diff: @@ -147,6 +147,14 @@ int main(int, char **)
  &testVar, 1u, 1u, 1u);
  }
  + // core/base/reflection.hpp
  + {
  + using type1 = int;
  + static_assert(
  + std::is_same<gko::Reflection<type1>::value_type, type1>::value,
  + "Reflection.hpp not included properly");
  + }
  +
  // core/base/std_extensions.hpp
  {
  static_assert(std::is_same<gko::xstd::void_t<double>, void>::value,
  