Batch delete issue and improve tippy opts (#25253)

1. Add "batch delete" button for selected issues, close #22273
2. Address the review in
https://github.com/go-gitea/gitea/pull/25219#discussion_r1229266083

routers/web/web.go

@@ -1024,6 +1024,7 @@ func registerRoutes(m *web.Route) {
 			m.Post("/request_review", reqRepoIssuesOrPullsReader, repo.UpdatePullReviewRequest)
 			m.Post("/dismiss_review", reqRepoAdmin, web.Bind(forms.DismissReviewForm{}), repo.DismissReview)
 			m.Post("/status", reqRepoIssuesOrPullsWriter, repo.UpdateIssueStatus)
+			m.Post("/delete", reqRepoAdmin, repo.BatchDeleteIssues)
 			m.Post("/resolve_conversation", reqRepoIssuesOrPullsReader, repo.UpdateResolveConversation)
 			m.Post("/attachments", repo.UploadIssueAttachment)
 			m.Post("/attachments/remove", repo.DeleteAttachment)