API: Improve MarshalToJson() in common/reflect/marshal.go (#3655)

* Serialize enum to string in MarshalToJson().

* MarshalToJson() respect json tags.

* Add insertTypeInfo parameter to MarshalToJson().

* Omit empty string in MarshalToJson().

* Serialize PortList to string in MarshalToJson().

---------

Co-authored-by: nobody <nobody@nowhere.mars>

infra/conf/serial/builder.go

@@ -17,7 +17,7 @@ func MergeConfigFromFiles(files []string, formats []string) (string, error) {
 		return "", err
 	}
 
-	if j, ok := creflect.MarshalToJson(c); ok {
+	if j, ok := creflect.MarshalToJson(c, true); ok {
 		return j, nil
 	}
 	return "", errors.New("marshal to json failed.").AtError()