Applying global phase multiplication to initialize operation

[doichanj]

Summary

This PR is fix for issue #1977

Details and comments

The global phase variable was not multiplied after initialize operation, this fix multiplies the global phase to the state in initialize operation.
Also matrix_product_state method did not use global phase, so this PR adds support of global phase in MPS method

[hhorii]

I think we do not need to change this method signature:

template <class state_t>
void Executor<state_t>::apply_initialize(const reg_t &qubits,
                                         const cvector_t &params_,
                                         RngEngine &rng) {
  auto sorted_qubits = qubits;
  std::sort(sorted_qubits.begin(), sorted_qubits.end());

  cvector_t tmp;
  // apply global phase here
  if (Base::states_[0].has_global_phase()) {
    tmp.resize(params.size());
    for (int_t i = 0; i < params.size(); i++) {
      tmp[i] = params[i] * Base::states_[0].global_phase();
    }
  }
  const cvector_t& params = tmp.empty() ? params_: tmp;

omp parallel maybe necessary if param exceeds a threshold.