Refactor htmx and fetch-action related code (#37186)

This is the first step (the hardest part):

* repo file list last commit message lazy load
* admin server status monitor
* watch/unwatch (normal page, watchers page)
* star/unstar (normal page, watchers page)
* project view, delete column
* workflow dispatch, switch the branch
* commit page: load branches and tags referencing this commit

The legacy "data-redirect" attribute is removed, it only makes the page
reload (sometimes using an incorrect link).

Also did cleanup for some devtest pages.

web_src/js/features/repo-issue-pull.ts

@@ -11,7 +11,6 @@ function initRepoPullRequestUpdate(el: HTMLElement) {
   const prUpdateDropdown = prUpdateButtonContainer.querySelector(':scope > .ui.dropdown')!;
   prUpdateButton.addEventListener('click', async function (e) {
     e.preventDefault();
-    const redirect = this.getAttribute('data-redirect');
     this.classList.add('is-loading');
     let response: Response | undefined;
     try {
@@ -29,8 +28,6 @@ function initRepoPullRequestUpdate(el: HTMLElement) {
     }
     if (data?.redirect) {
       window.location.href = data.redirect;
-    } else if (redirect) {
-      window.location.href = redirect;
     } else {
       window.location.reload();
     }