feat: the text of the optimized tree item is too long (#773)

Author: Zaoei

src/components/tree/style.scss

@@ -28,6 +28,9 @@ $treenode-height: 22px;
 
         &__title {
             margin-left: 5px;
+            overflow: hidden;
+            text-overflow: ellipsis;
+            white-space: nowrap;
             width: 100%;
         }