Add Enum EventType implementation code

issue:https://gitee.com/openharmony/js_api_module/issues/I59MKH
Signed-off-by: lihucheng <lihucheng1@huawei.com>

xml/src/js_xml.ts

@@ -192,7 +192,22 @@ class XmlPullParser {
     }
 }
 
+enum EventType {
+    START_DOCUMENT,
+    END_DOCUMENT,
+    START_TAG,
+    END_TAG,
+    TEXT,
+    CDSECT,
+    COMMENT,
+    DOCDECL,
+    INSTRUCTION,
+    ENTITY_REFERENCE,
+    WHITESPACE
+}
+
 export default {
     XmlSerializer : XmlSerializer,
     XmlPullParser : XmlPullParser,
+    EventType,
 }