Refactor LabelEdit (#32752)

And fix a regression:
https://github.com/go-gitea/gitea/pull/30053#discussion_r1874405470

Major changes:

* rewrite without jquery
* remove the "delete modal", using "link-action" is good enough
* merge "new modal" and "edit modal"

web_src/js/features/repo-legacy.ts

@@ -43,7 +43,7 @@ export function initRepository() {
   initRepoCommentFormAndSidebar();
 
   // Labels
-  initCompLabelEdit('.repository.labels');
+  initCompLabelEdit('.page-content.repository.labels');
   initRepoMilestone();
   initRepoNew();