Combines GetPreimage and GetOracleData into GetStepData. GetStepData returns the data needed to execute the step at the specified trace index, so the state is the pre-state rather than matching the claim at the specified index. The proof data contains proofs for data accessed while executing the step and oracle data the pre-images required to execute the step. This matches up correctly with the data in the cannon proof files and what is required when calling the step function.