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.

modules/web/middleware/cookie.go

@@ -35,6 +35,11 @@ func DeleteRedirectToCookie(resp http.ResponseWriter) {
 }
 
 func RedirectLinkUserLogin(req *http.Request) string {
+	if req.Header.Get("X-Gitea-Fetch-Action") != "" {
+		// when building the redirect link for a fetch request, the current link might be a partial page,
+		// so we only redirect to the login page without redirect_to parameter
+		return setting.AppSubURL + "/user/login"
+	}
 	return setting.AppSubURL + "/user/login?redirect_to=" + url.QueryEscape(setting.AppSubURL+req.URL.RequestURI())
 }