feat: remove fomantic's tab module (#8587)

In similar vein of forgejo/forgejo#7416

- Fomantic's tab module is responsible for showing the right content when a tab is clicked upon. Most notably the Write/Preview tabs on the comment editor.
- Remove it and replace the javascript with our own function that is able to provide everything Forgejo needs.
- Replace the CSS with our own bare minimum CSS.
- No functionality or visual is affected by this replacement.
- E2E test added.

Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/8587
Reviewed-by: Otto <otto@codeberg.org>
Reviewed-by: 0ko <0ko@noreply.codeberg.org>
Co-authored-by: Gusted <postmaster@gusted.xyz>
Co-committed-by: Gusted <postmaster@gusted.xyz>

web_src/js/features/common-global.js

@@ -12,6 +12,7 @@ import {confirmModal} from './comp/ConfirmModal.js';
 import {showErrorToast} from '../modules/toast.js';
 import {request, POST, GET} from '../modules/fetch.js';
 import '../htmx.js';
+import {initTab} from '../modules/tab.ts';
 
 const {appUrl, appSubUrl, csrfToken, i18n} = window.config;
 
@@ -195,7 +196,9 @@ export function initGlobalCommon() {
   $uiDropdowns.filter('.upward').dropdown('setting', 'direction', 'upward');
   $uiDropdowns.filter('.downward').dropdown('setting', 'direction', 'downward');
 
-  $('.tabular.menu .item').tab();
+  for (const el of document.querySelectorAll('.tabular.menu')) {
+    initTab(el);
+  }
 
   initSubmitEventPolyfill();
   document.addEventListener('submit', formFetchAction);