Implement initialization of a single qubit from a cudaq::state object

[schweitzpgi]

This corner case needs to be implemented and a test added. The implementation must verify that the state object contains 2 complex values.

#include <cudaq.h>

__qpu__ void qernel(cudaq::state &aState) {
  cudaq::qubit q = aState;
  ...
}

See #1086