Function encode_flow_state 

pub fn encode_flow_state(
    sender: NodeId,
    session: LinkSessionId,
    state: FlowState,
    output: &mut [u8],
    limits: WireLimits,
) -> Result<ControlEncoding, WireError>

Encode a REPLICA_STATE response/notification without allocating or granting authority. Local retention bounds are independent of the maximum size of one wire frame.