修复sncpAsyncGroup未启动的bug

src/main/java/org/redkale/boot/NodeServer.java

@@ -857,6 +857,9 @@ public abstract class NodeServer {
         if (interceptor != null) {
             interceptor.preStart(this);
         }
+        if (this.sncpAsyncGroup != null) {
+            this.sncpAsyncGroup.start();
+        }
         server.start();
         postStartServer(localServices, remoteServices, servletServices);
     }

src/main/java/org/redkale/util/ByteArray.java

@@ -1148,6 +1148,10 @@ public final class ByteArray implements ByteTuple {
         return new String(content, 0, count);
     }
 
+    public String toUTF8String() {
+        return new String(content, 0, count, StandardCharsets.UTF_8);
+    }
+
     /**
      * 按指定字符集转成字符串
      *