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/admin/common.ts

@@ -285,6 +285,6 @@ function initAdminNotice() {
       }
     }
     await POST(this.getAttribute('data-link')!, {data});
-    window.location.href = this.getAttribute('data-redirect')!;
+    window.location.reload();
   });
 }