Add circuit to_cirq and from_cirq functionality

[refraction-ray]

Task description

Similar to AbstractCircuit.to_qiskit method, ultimately we would like to transform tensorcircuit Circuit with cirq Circuit as well.

Implementation

Add functions similar to qir2qiskit in https://github.com/tencent-quantum-lab/tensorcircuit/blob/master/tensorcircuit/translation.py. And then add a wrapper method in https://github.com/tencent-quantum-lab/tensorcircuit/blob/master/tensorcircuit/abstractcircuit.py as .to_cirq and .from_cirq.
Add test similar to https://github.com/tencent-quantum-lab/tensorcircuit/blob/master/tests/test_circuit.py#L845 accordingly.

Requirements

Difficulty: ★★★

[JettChenT]

Hi! I'm willing to work on this issue.
After a look in the code base, the to_cirq and qir2cirq functionalities are already implemented in #106 .

I suppose I can work on from_cirq? Thanks!

[refraction-ray]

@JettChenT , thanks for your interest, feel free to contribute and open pr on this issue!

For to_cirq, the implementation now is not complete in terms of different gates, at least we need an equivalent translation of commonly used rxx, ryy, rzz gates which is lacking now.
And we now have no function for from_cirq which is also welcome to contribute.

[JettChenT]

Got it, thanks!