Use Okta for OIDC authentication

[!IMPORTANT]
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1. Make sure an Authorization Server has been created. The "Issuer" field shown on the Setting page will be used as the oidc_discovery_url.
2. Visit Applications > Add Application (Web).
3. Configure Login redirect URIs. Save.
4. Save client ID and secret.

Note your policy will need oidc_scopes to include profile to get a full profile ("Fat Token"). You will also need to configure bound audience along the lines of "bound_audiences": ["api://default", "0a4........."] if you are using the default authorization server.