(bb.js): Incorporate dummy backend to nargo that can interop with bb.js

[vezenovm]

Problem

With barretenberg's move to bb.js there is a divergence in how the new binary expects a circuit to be serialized and the barretenberg structures it expects (bb.js has recursion while acvm-backend-barretenberg) does not. We need a backend that has the structures bb.js expects and the respective serialization.

Happy Case

The previous way of building nargo with acvm-backend-barretenberg should remain the same. If some wishes to compile Noir into the format that bb.js expects they should build nargo using cargo install --path=crates/nargo_cli --no-default-features --features=bb_js. This will be an advanced user feature until bb.js is integrated into nargo. A user should then be able to do nargo compile <CIRCUIT_NAME> and nargo execute witness to interop with bb.js which expects a circuit json file and a witness file.

The tech debt from this dummy backend should be minimal and easy to reverse.

Alternatives Considered

We will eventually move to incorporating bb.js into nargo and then to a final solution once dynamic backends are fully ready. This is a temporary solution to get bb.js (which included the low-memory prover and recursion) integrated with Noir, and will be moved away from.

The current dummy backend also does not handle methods that require simulation such as pedersen. This will most likely only come once we have a clean way for nargo to interop with bb.js.

Additional Context

No response

Would you like to submit a PR for this Issue?

Yes

Support Needs

No response

[Savio-Sou]

Superseded by #1569?

[kevaundray]

Superseded by #1569?

Yep

[vezenovm]

This PR #1876 when used with this serialization tool https://github.com/vezenovm/acir-to-bberg-circuit should get Noir master in line with bb.js