feat(circuits): add QAOAPathCircuit class

[pedrorrivero]

Summary

Adds new QAOAPathCircuit class to create parameterized QAOA quantum circuits for path acyclic graphs, at varying number of qubits and two-qubit depth.

Details and comments

• This is a utility class to avoid building these (well-known) circuits manually in present and upcoming notebooks.
• Needed for the Utility Scaling notebook, demoed at IBM Quantum Practitioner's Forum 2023.

[coveralls]

Pull Request Test Coverage Report for Build 8441529388

Details

• 41 of 41 (100.0%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 100.0%

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Totals
Change from base Build 8441486427:	0.0%
Covered Lines:	60
Relevant Lines:	60

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💛 - Coveralls

[a-matsuo]

I left some comments. It seems good. However, the name, 'QAOALineCircuit' might need to change.

[a-matsuo]

LGTM!