IonQ and Quantinuum notebooks

[Sam-XiaoyueLi]

This PR added notebooks to:

1. Synthesize VQE+GCI circuits in [qasm] from notebooks/gci_boostvqe_circuit_synthesis.ipynb
2. Load the qasm files in qiskit and pytket and run IonQ/Nexus simulations for the XXZ model in
   notebooks/ionq_demo and notebooks/quantinuum_demo
3. Analyze the simulation results
   e.g. for IonQ

This comes in form of interactive notebooks because it is meant to cater for outside users who might want to tinker with our circuits using other APIs.

In the results folder under notebooks, there are 3 categories of files:

1. VQE trained parameters (.npy), which are used for constructing the VQE circuits.
2. VQE/GCI circuits (.qasm) are qasm files that contain the circuit configurations converted from Qibo. They can be loaded into both qiskit and pytket circuit formats as shown in the notebooks.
3. Quantinuum Nexus local job references, execute_job_.. are stored so that the quantinuum execution results can be easily retrieved from our interactive notebooks.