Enable local zk proof generation

[nuke-web3]

The eq-service presently only supports using the succinct prover network and this required a whitelisted key to use.
As an alternative, allowing the ability to generate a proof on the machine running the eq-service would be beneficial:

• Acts as a failsafe when the prover network is problematic
• Enables a "Free" option, as no funs/whitelisting is required to generate a proof
• Abstract interface to ZK proof generation service
  • A trait impl for local is likley the best way to write this up IMHO

Perhaps a the gRPC call level, we would allow to selection of an explict prover service (local, network, what proof system/zkVM etc.). Alt/in addition would be to have the operator of eq-service select that (default & fallback) in config.