* op-challenger: Load required data for blob preimages

* op-challenger: Support posting blob preimages to the oracle contract.

* op-challenger: Use actual oracle data when computing proof.

* op-challenger: Test rejecting invalid blob value

* Unextract method - it wasn't required.

* op-challenger: Load commitment and required field element from the key preimage rather than the hint
op-program: Store the preimage of the field element key so it is available to the challenger

* op-challenger: Improve testing. Use geth KZG utils to avoid creating a new kzg context.