Enable pylint's unused-argument check

[garrison]

Closes #319.

I changed CutQC's _print_cutter_result to display num_cuts as well (previously, it ignored it). In passing, I also removed the num_subcircuit argument to this function, as it was redundant with len(subcircuits).

In other files, I prefixed intentionally ignored arguments with unused_ or ignored_ so pylint will ignore them.

[garrison]

Heh, there remains one more unused argument: num_threads at https://qiskit-extensions.github.io/circuit-knitting-toolbox/circuit_cutting/cutqc/tutorials/tutorial_3_cutting_with_quantum_serverless.html. I went ahead and removed it -- seemed like the most obvious way to handle this.

[caleb-johnson]

Thanks, LGTM