Required to extend test coverage for std::complex operations

[SergeyKopienko]

Required to extend test coverage for std::complex operations: https://en.cppreference.com/w/cpp/numeric/complex/operator_arith, https://en.cppreference.com/w/cpp/numeric/complex/operator_arith2, https://en.cppreference.com/w/cpp/numeric/complex/operator_arith3, https://en.cppreference.com/w/cpp/numeric/complex/operator_cmp, https://en.cppreference.com/w/cpp/numeric/complex/operator%3D, https://en.cppreference.com/w/cpp/numeric/complex/operator_ltltgtgt and some other functions.