Conversion between Qiskit and TKET Quantum Circuit formats

[nquetschlich]

Frequently, we need to convert Qiskit.QuantumCircuit objects to pytket.Circuit objects. Since the underlying qiskit_to_tkmethod from pytket-qiskit is not perfect, we have to work with workarounds at various places in MQT Bench. It would be desired to improve those parts of the code, especially when a Qiskit.transpilecall is used before the conversion to avoid errors (e.g., https://github.com/CQCL/pytket-qiskit/issues/138).