Function process_message 

pub async fn process_message(
    incoming: Incoming,
    registry: &Registry,
    set_slot_values_handler: &Option<SetSlotValuesHandler>,
    get_slot_values_handler: &Option<GetSlotValuesHandler>,
    validate_paths: bool,
) -> Outgoing

Process an incoming message and return the response.

This function is public so it can be reused by other connection types (e.g., WebAppServer) that share the same arora protocol.