message: cli: add multiwallet capability to GetNewAddress and -generate
diff: @@ -538,8 +538,10 @@ static void GetWalletBalances(UniValue& result)
  */
  static UniValue GetNewAddress()
  {
  + Optional<std::string> wallet_name{};
  + if (gArgs.IsArgSet("-rpcwallet")) wallet_name = gArgs.GetArg("-rpcwallet", "");
  std::unique_ptr<BaseRequestHandler> rh{MakeUnique<DefaultRequestHandler>()};
  - return ConnectAndCallRPC(rh.get(), "getnewaddress", /* args=*/{});
  + return ConnectAndCallRPC(rh.get(), "getnewaddress", /* args=*/{}, wallet_name);
  }
  /**
  