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/gitea-ui.tmpl

@@ -45,17 +45,6 @@
 					</div>
 				</li>
 			</ul>
-			<script>
-				document.addEventListener('gitea:index-ready', () => {
-					const $buttons = $('#devtest-button-samples').find('button.ui');
-
-					const $buttonStyles = $('input[name*="button-style"]');
-					$buttonStyles.on('click', () => $buttonStyles.map((_, el) => $buttons.toggleClass(el.value, el.checked)));
-
-					const $buttonStates = $('input[name*="button-state"]');
-					$buttonStates.on('click', () => $buttonStates.map((_, el) => $buttons.prop(el.value, el.checked)));
-				});
-			</script>
 		</div>
 	</div>