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.

templates/devtest/fetch-action.tmpl

@@ -3,7 +3,7 @@
 	<div>
 		<h1>link-action</h1>
 		<div>
-			Use "window.fetch" to send a request to backend, the request is defined in an "A" or "BUTTON" element.
+			The request is defined in an "A" or "BUTTON" element.
 			It might be renamed to "link-fetch-action" to match the "form-fetch-action".
 		</div>
 		<div>
@@ -15,7 +15,6 @@
 	</div>
 	<div>
 		<h1>form-fetch-action</h1>
-		<div>Use "window.fetch" to send a form request to backend</div>
 		<div class="flex-relaxed-list fetch-action-demo-forms">
 			<form method="get" action="./fetch-action-test?k=1" class="form-fetch-action">
 				<button name="btn">submit get</button>
@@ -25,7 +24,7 @@
 				<div><label><input name="check" type="checkbox"> check</label></div>
 				<div><button name="btn">submit post</button></div>
 			</form>
-			<form method="post" action="./no-such-uri" class="form-fetch-action">
+			<form method="post" action="/-/no-such-uri" class="form-fetch-action">
 				<div class="tw-py-8">bad action url</div>
 				<div><button name="btn">submit test</button></div>
 			</form>