[web] Fetch favicons from CDN (#28419)

* Simplify paths in `buildImgPath`

* Move favicons from `public` to `public/img/favicons`

* Create links to favicons in `public` (`ln -s img/favicons/* .`)

* Import favicons dynamically in use-status-favicon.ts

* Update pug files with cdn favicon paths

* Update test

* Revert change in layout-no-js.pug

* Fetch web.sitemanifest from CDN

* Revert favicon move

* Fix favicon paths (use `buildBaseAssetPath`)

* Fixup web.sitemanifest path

* Format

* Update `buildImgPath` mock to be more realistic

* Revert web.sitemanifest link to local origin

* Revert "Revert web.sitemanifest link to local origin"

This reverts commit aa13431b743b55c2f536c33e736f657e1c0db598.

GitOrigin-RevId: fe278fec0f1eaae16de9fabc2b13da3e7a316463

services/web/test/frontend/features/ide-react/unit/use-status-favicon.test.ts

@@ -53,6 +53,11 @@ describe('useStatusFavicon', function () {
     document
       .querySelectorAll('link[data-compile-status="true"]')
       .forEach(el => el.remove())
+
+    window.metaAttributesCache.set(
+      'ol-baseAssetPath',
+      'https://cdn.test-overleaf.com/'
+    )
   })
 
   afterEach(function () {