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/index.ts

@@ -185,5 +185,3 @@ document.body.addEventListener('htmx:responseError', (event) => {
   // TODO: add translations
   showErrorToast(`Error ${(event as HtmxEvent).detail.xhr.status} when calling ${(event as HtmxEvent).detail.requestConfig.path}`);
 });
-
-document.dispatchEvent(new CustomEvent('gitea:index-ready'));