What should we add?

convert_to_target doesn't currently look at operational and faulty_{qubits,gates} fields. Target nominally has support for these by removing faulty gates from each qubit, but this needs to be done while constructing the Target. Handling these within convert_to_target would allow for compiling against backends with faulty qubits.

(N.B. Executing jobs against these backends would still require an additional step of re-indexing compiled circuits to the original qubit indicies, but that may be eased by #9851 ).