Support end-to-end flow with Bonsai in forge test and local deployment

[nategraf]

This PR ports the modifications and improvements I worked on for the Governance showcase back to the template. Included changes are:

• In forge test, optional request a SNARK from the Bonsai proving service and provide it to authenticate the callback, using the real SNARK verifier implementation (BonsaiRelay). This flow is enabled when RISC0_DEV_MODE=false is set and uses the full implementations of all components except the Bonsai Relay.
• By running cargo run --bin bonsai-ethereum-relay-cli -- run, developers can launch the Bonsai relay. With this, they can either target a a local Ethereum node with anvil or a public Ethereum network like Sepolia. This supports both local and testnet deployment of the developers's application.

Additionally:

• Declare github.com/risc0/risc0 as a dependency and use the contained Bonsai libraries.
• Format and add new content to README.md
• Use workspace-level dependency declarations.

Resolves https://github.com/risc0/bonsai-foundry-template/issues/26 Resolves https://github.com/risc0/bonsai-foundry-template/issues/27 Resolves https://github.com/risc0/bonsai-foundry-template/issues/28

[nategraf]

Remaining work is to update and test the local deployment script. If it is ready, I will also integrate the updated relay with the ability to plumb through SNARK proofs from the Bonsai proving service.

[nategraf]

Depends on additions to the Bonsai libraries in https://github.com/risc0/risc0/pull/712

[nategraf]

@capossele, I've now added a more complete deploy script and run the local deployment. The local environment example doesn't work yet because the Relay does not support the BonsaiRelay and BonsaiTestRelay contracts.

[capossele]

Replaced by #45