Function init 

pub async fn init<Rpc, ReadStateService, Mempool, Tip>(
    listen_addr: SocketAddr,
    rpc: Rpc,
    read_state: ReadStateService,
    mempool: Mempool,
    latest_chain_tip: Tip,
    mempool_change: MempoolTxSubscriber,
    network: Network,
) -> Result<(JoinHandle<Result<(), BoxError>>, SocketAddr), BoxError>
where
    Rpc: RpcMethods + Clone,
    ReadStateService: ReadState,
    Mempool: MempoolService,
    Tip: ChainTip + Clone + Send + Sync + 'static,

Initializes the lightwalletd gRPC server.