Allow for local proving

[JossDuff]

op-proposer has a command line arg OP_SUCCINCT_SERVER_URL that allows for requesting proofs to provers other than the proving network, but the proposer/succinct proving server middleware only allows for forwarding requests to the proving network or mock proofs. But myself and others might want to either run proofs locally for benchmarking or if we want to host our own prover.

To do some local testing and benchmarking we modified proposer/succinct/bin/server.rs and proposer/succinct/src/lib.rs to request the proof via ProverClient::prove(...) which runs the proof locally by default. The changes were pretty trivial and others might find them useful. I'd be happy to open a pr with this and any modifications that might be necessary :)

[ratankaliani]

Hey! Is there a reason why you want to bench locally vs. on the proving network? OP Succinct workloads perform better on the proving network because it can scale up to meet demand horizontally. Will DM.

Feel free to put up a PR with the diff, happy to review & merge :)