Allow Generator object for seed in QuantumVolume circuit

[chriseclectic]

Summary

Allows passing in a Numpy random Generator object as seed value for QuantumVolume circuit.

Closes #4866

Details and comments

[mtreinish]

This LGTM, but can you add a release note about support for passing a generator (and also maybe about the name change).

[nonhermitian]

It would be nice if the circuit name had the seed and the offset from this seed in the name. Then each circuit could be reconstructed from the name alone.

[chriseclectic]

@nonhermitian As far as i know this info can't be extract from the PCG64 Generator since it doesn't actually use an integer seed internally but using the int to generate a SeedSequence to generate a BitGenerator.

[nonhermitian]

I am basically advocating for something like I did here:

https://github.com/Qiskit/qiskit-terra/blob/81216e55b339ef0cdab50d43d116eeb261dff540/qiskit/circuit/library/quantum_volume.py#L95

where the seed used to start the generator is attached to the circuit, plus the number of times the generator was called. Flor example if the seed was 2231, and I just seeded (offset=0) it then the name would be like QuantumVolume_10x10_2231+0.

With this convention I can reproduce the circuit, I would just re-seed with the same seed, and then call offset number of times before generating the circuit.