frontend: index.html: Add crossorigin attribute to manifest link

Adds crossorigin="use-credentials" to the manifest link so that cookies
are sent when fetching manifest.json. This fixes issues where Headlamp
is hosted behind an authentication proxy (like Authelia).

Fixes #4572

Signed-off-by: zyzzmohit <mohitray949@gmail.com>

Author: zyzzmohit

frontend/index.html

@@ -16,7 +16,7 @@
       manifest.json provides metadata used when your web app is installed on a
       user's mobile device or desktop. See https://developers.google.com/web/fundamentals/web-app-manifest/
     -->
-    <link rel="manifest" href="/manifest.json" />
+    <link rel="manifest" href="/manifest.json" crossorigin="use-credentials" />
     <!--
       Unlike "/favicon.ico" or "favicon.ico", "/favicon.ico" will
       work correctly both with client-side routing and a non-root public URL.