add and use window.config.isSignedIn

Author: silverwind

templates/base/head_script.tmpl

@@ -15,6 +15,7 @@ If you introduce mistakes in it, Gitea JavaScript code wouldn't run correctly.
 		runModeIsProd: {{.RunModeIsProd}},
 		customEmojis: {{CustomEmojis}},
 		csrfToken: '{{.CsrfToken}}',
+		isSignedIn: {{.IsSigned}},
 		pageData: {{.PageData}},
 		notificationSettings: {{NotificationSettings}}, {{/*a map provided by NewFuncMap in helper.go*/}}
 		enableTimeTracking: {{EnableTimetracking}},

web_src/js/features/repo-issue-list.js

@@ -8,6 +8,7 @@ import {createSortable} from '../modules/sortable.js';
 import {DELETE, POST} from '../modules/fetch.js';
 
 function initRepoIssueListCheckboxes() {
+  if (!window.config.isSignedIn) return;
   const issueSelectAll = document.querySelector('.issue-checkbox-all');
   const issueCheckboxes = document.querySelectorAll('.issue-checkbox');