`provekit/common/src/witness/witness_generator`: Handling of the return value for the verifier.

[recmo]

On 2025-08-29 in 2a57572 “Merge pull request #153 from worldfnd/px/refactor”:

Handling of the return value for the verifier.

    noirc_abi::Abi,
    serde::{Deserialize, Serialize},
    std::num::NonZeroU32,
};

// TODO: Handling of the return value for the verifier.

#[derive(Clone, Debug, Serialize, Deserialize)]
pub struct NoirWitnessGenerator {
    // Note: Abi uses an [internally tagged] enum format in Serde, which is not compatible
    // with some schemaless formats like Postcard.

From provekit/common/src/witness/witness_generator.rs:8