Never use /api/v1 from Gitea UI Pages (#19318)

Reusing `/api/v1` from Gitea UI Pages have pros and cons.
Pros:
1) Less code copy

Cons:
1) API/v1 have to support shared session with page requests.
2) You need to consider for each other when you want to change something about api/v1 or page.

This PR moves all dependencies to API/v1 from UI Pages.

Partially replace #16052

web_src/js/components/ContextPopup.vue

@@ -120,7 +120,7 @@ export default {
     load(data, callback) {
       this.loading = true;
       this.i18nErrorMessage = null;
-      $.get(`${appSubUrl}/api/v1/repos/${data.owner}/${data.repo}/issues/${data.index}`).done((issue) => {
+      $.get(`${appSubUrl}/${data.owner}/${data.repo}/issues/${data.index}/info`).done((issue) => {
         this.issue = issue;
       }).fail((jqXHR) => {
         if (jqXHR.responseJSON && jqXHR.responseJSON.message) {