Added a QITE TFIM example

#include "qcor_qsim.hpp"

int main(int argc, char** argv) {

  set_verbose(true);

  using namespace QuaSiMo;

  // Create the qsearch IR Transformation

  auto qsearch_optimizer = createTransformation("qsearch");

  // Create the Hamiltonian: 3-qubit TFIM

  auto observable = Z(0) * Z(1) + Z(1) * Z(2) + X(0) + X(1) + X(2);

  observable *= -1;

  // We'll run with 20 steps and .45 step size

  const int nbSteps = 20;

  const double stepSize = 0.45;

  auto problemModel = ModelFactory::createModel(&observable);

  // With circuit optimization (QSearch)

  // auto workflow =

  //     getWorkflow("qite", {{"steps", nbSteps},

  //                          {"step-size", stepSize},

  //                          {"circuit-optimizer", qsearch_optimizer}});

  // Without circuit optimization 

  auto workflow =

      getWorkflow("qite", {{"steps", nbSteps}, {"step-size", stepSize}});

  // Execute

  auto result = workflow->execute(problemModel);

  // Get the energy and final circuit

  const auto energy = result.get<double>("energy");

  auto finalCircuit = result.getPointerLike<CompositeInstruction>("circuit");

  printf("\n%s\nEnergy=%f\n", finalCircuit->toString().c_str(), energy);

}

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