Add label/author/assignee filters to the user/org home issue list (#32779)

Replace #26661, fix #25979

Not perfect, but usable and much better than before. Since it is quite
complex, I am not quite sure whether there would be any regression, if
any, I will fix in first time.

I have tested the related pages many times: issue list, milestone issue
list, project view, user issue list, org issue list.

routers/web/web.go

@@ -1208,7 +1208,7 @@ func registerRoutes(m *web.Router) {
 					Post(web.Bind(forms.CreateIssueForm{}), repo.NewIssuePost)
 				m.Get("/choose", context.RepoRef(), repo.NewIssueChooseTemplate)
 			})
-			m.Get("/search", repo.ListIssues)
+			m.Get("/search", repo.SearchRepoIssuesJSON)
 		}, context.RepoMustNotBeArchived(), reqRepoIssueReader)
 
 		// FIXME: should use different URLs but mostly same logic for comments of issue and pull request.