Use shallowRef instead of ref in .vue files where possible (#34813)

This PR improves some `.vue` components by using `shallowRef instead of
ref`, which `should improve performance`. It's probably not significant,
but it's an improvement because Vue no longer deep watches the ref
(shallowRef). Also i used `useTemplateRef` instead of `ref`.

---------

Signed-off-by: wxiaoguang <wxiaoguang@gmail.com>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

web_src/js/components/ViewFileTree.vue

@@ -1,9 +1,9 @@
 <script lang="ts" setup>
 import ViewFileTreeItem from './ViewFileTreeItem.vue';
-import {onMounted, ref} from 'vue';
+import {onMounted, useTemplateRef} from 'vue';
 import {createViewFileTreeStore} from './ViewFileTreeStore.ts';
 
-const elRoot = ref<HTMLElement | null>(null);
+const elRoot = useTemplateRef('elRoot');
 
 const props = defineProps({
   repoLink: {type: String, required: true},