Add apply_layout to PauliList

[chriseclectic]

What should we add?

An apply_layout method was recently added to the Pauli operator, but not to a PauliList. PauliList is a convenient input for EstimatorV2 to represent a 1D list of Pauli's to measure, so should also have an apply_layout method.

Eg to measure Z operators on each single qubit in a list of N-qubits mapped to a bigger device one should be able to do:

obs = PauliList.from_symplectic(np.eye(N), np.zeroes((N, N))).apply_layout(isa_circuit.layout)

[garrison]

Cross-referencing #11824, as the current issue is a specific subcase of that one.

Having this proposed feature would be desirable in the circuit-knitting-toolbox for a how-to guide I am writing: Qiskit-Extensions/circuit-knitting-toolbox#573 (comment). In the meantime, we will either need to unnecessarily create a SparsePauliOp from the PauliList in order to call SparsePauliOp.apply_layout, or provide users with a utility function in CKT that can apply a TranspileLayout to a PauliList.

Our PauliList represents a list of Pauli terms restricted to one subsystem of the cut circuit. We could iterate and apply this to each Pauli individually, but it will be more efficient (and more succinct) to be able to do this without having to convert it away from a PauliList.