rpcserver: send pending channels to aux data parser

We added the custom data to the pending channels but forgot to also
send the response RPC message to the custom channel parser so it can
turn it into human-readable JSON.

rpcserver.go

@@ -4180,6 +4180,16 @@ func (r *rpcServer) PendingChannels(ctx context.Context,
 	resp.WaitingCloseChannels = waitingCloseChannels
 	resp.TotalLimboBalance += limbo
 
+	err = fn.MapOptionZ(
+		r.server.implCfg.AuxDataParser,
+		func(parser AuxDataParser) error {
+			return parser.InlineParseCustomData(resp)
+		},
+	)
+	if err != nil {
+		return nil, fmt.Errorf("error parsing custom data: %w", err)
+	}
+
 	return resp, nil
 }