Refactor branch/tag selector to Vue SFC (#23421)

Follow #23394

There were many bad smells in old code. This PR only moves the code into
Vue SFC, doesn't touch the unrelated logic.

update: after
5f23218c85
, there should be no usage of the vue-rumtime-compiler anymore
(hopefully), so I think this PR could close #19851

---------

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

web_src/js/components/DashboardRepoList.vue

@@ -73,7 +73,7 @@
           <li v-for="repo in repos" :class="{'private': repo.private || repo.internal}" :key="repo.id">
             <a class="repo-list-link gt-df gt-ac gt-sb" :href="repo.link">
               <div class="item-name gt-df gt-ac gt-f1 gt-mr-2">
-                <svg-icon :name="repoIcon(repo)" size="16" class-name="gt-mr-2"/>
+                <svg-icon :name="repoIcon(repo)" :size="16" class-name="gt-mr-2"/>
                 <div class="text gt-bold truncate gt-ml-1">{{ repo.full_name }}</div>
                 <span v-if="repo.archived">
                   <svg-icon name="octicon-archive" :size="16" class-name="gt-ml-2"/>