Allow exchange of oidc access token for app password

[akhil1508]

• In the nextcloud login flow, we can use a regular password to exchange for an app password: https://docs.nextcloud.com/server/latest/developer_manual/client_apis/LoginFlow/index.html#converting-to-app-passwords
• Would be nice if we could exchange an OIDC access token for an app password too
• Would allow for the client session to show up in settings/user/security even if token is obtained from another client in the same realm (looking at the mobile device use case with aud configured correctly)