feat: make worker more "stateless"

[lispc]

When a worker starts, it only knows the coordinator url.

Then it fetches a task from the coordinator, {circuit_id, witness}. If it does not know about the circuit, then it fetches the circuit information from the coordinator ( req: circuit_id, resp: { r1cs_url, srs_monomial_form_url, srs_lagrange_form_url} ). Then the worker can save the circuit locally ( both memory and local file is ok ).

( url can be s3 url or http url )

worked_id is generated as uuid locally.

[lispc]

We may need to prove different circuits in the future ( block / exit tree , of different size / n_tx ) . So fetching circuit details from master seems more flexible ?

[0xmountaintop]

for now a client 100% know the circuit because it query from coordinator by task.

    pub async fn poll_task(&self) -> Result<Task, anyhow::Error> {
        let mut client = ClusterClient::connect(self.upstream.clone()).await?;

        let request = tonic::Request::new(PollTaskRequest {
            prover_id: self.id.clone(),
            circuit: self.circuit as i32,
            timestamp: chrono::Utc::now().timestamp_millis(),
        });

        log::info!("prover({}) polling task", self.id);
        match client.poll_task(request).await {
            Ok(t) => Ok(t.into_inner()),
            Err(e) => Err(anyhow!(e)),
        }
    }