Use fetch helpers instead of fetch (#27026)

WIP because:

- [x] Some calls set a `content-type` but send no body, can likely
remove the header
- [x] Need to check whether `charset=utf-8` has any significance on the
webauthn calls, I assume not as it is the default for json content.
- [x] Maybe `no-restricted-globals` is better for eslint, but will
require a lot of duplication in the yaml or moving eslint config to a
`.js` extension.
- [x] Maybe export `request` as `fetch`, shadowing the global.

web_src/js/features/copycontent.js

@@ -1,6 +1,7 @@
 import {clippie} from 'clippie';
 import {showTemporaryTooltip} from '../modules/tippy.js';
 import {convertImage} from '../utils.js';
+import {GET} from '../modules/fetch.js';
 
 const {i18n} = window.config;
 
@@ -20,7 +21,7 @@ export function initCopyContent() {
     if (link) {
       btn.classList.add('is-loading', 'small-loading-icon');
       try {
-        const res = await fetch(link, {credentials: 'include', redirect: 'follow'});
+        const res = await GET(link, {credentials: 'include', redirect: 'follow'});
         const contentType = res.headers.get('content-type');
 
         if (contentType.startsWith('image/') && !contentType.startsWith('image/svg')) {