pwa-auth sample: silent

This sample shows how to use pwa-auth in credentialmode="silent", which enables fast, silent sign-in for users who had previously signed-in.

To see this in action:

1. Click Sign In and choose any provider (e.g. Microsoft)
2. Once you're signed in, the browser will prompt you to save your sign-in. Choose Save.
3. Refresh this page
4. Click Sign In again; you'll be automatically and silently signed-in, no prompts or dialogs.

Note: credentialmode relies on the new Credential Management APIs, see browser support. Older browsers will fallback to standard OAuth flows.