Add dense_asymm GEMM test for complex value tensors.

[tyzhang1993]

This PR adds complex-value GEMM test in ta_dense_asymm.cpp for benchmark purpose.

[tyzhang1993]

@evaleev I am trying to make this change of code for benchmark purpose. However, it does not compile with error message:

[ 98%] Building CXX object _deps/tiledarray-build/examples/dgemm/CMakeFiles/ta_dense_asymm.dir/ta_dense_asymm.cpp.o
In file included from /Users/zty/Source/chronusq_dev_github/build/_deps/tiledarray-src/examples/dgemm/ta_dense_asymm.cpp:21:
In file included from /Users/zty/Source/chronusq_dev_github/build/_deps/tiledarray-src/src/tiledarray.h:29:
In file included from /Users/zty/Source/chronusq_dev_github/build/_deps/tiledarray-src/src/TiledArray/tensor.h:33:
/Users/zty/Source/chronusq_dev_github/build/_deps/tiledarray-src/src/TiledArray/tensor/tensor_interface.h:1046:12: error: no viable conversion from returned value of type 'TiledArray::detail::TensorInterface<const std::complex<double>, TiledArray::Range, btas::Tensor<std::complex<double>, TiledArray::Range>>::numeric_type' (aka 'std::complex<double>') to function return type 'TiledArray::detail::TensorInterface<const std::complex<double>, TiledArray::Range, btas::Tensor<std::complex<double>, TiledArray::Range>>::scalar_type' (aka 'double')
    return reduce(square_op, sum_op, numeric_type(0));
           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/Users/zty/Source/chronusq_dev_github/build/_deps/tiledarray-src/src/TiledArray/external/btas.h:742:23: note: in instantiation of member function 'TiledArray::detail::TensorInterface<const std::complex<double>, TiledArray::Range, btas::Tensor<std::complex<double>, TiledArray::Range>>::squared_norm' requested here
  return make_ti(arg).squared_norm();
                      ^
/Users/zty/Source/chronusq_dev_github/build/_deps/tiledarray-src/src/TiledArray/tile.h:1515:10: note: in instantiation of function template specialization 'btas::squared_norm<std::complex<double>, TiledArray::Range, std::vector<std::complex<double>>>' requested here
  return squared_norm(arg.tensor());
         ^

Could you please help me with this? Thanks!

[evaleev]

subsumed by #397 ... TA::Tile<btas::Tensor<complex>> had some uses of numeric_type in place of scalar_type