Misleading IsLoggedIn implementation in OpenIDConnectService

[AKissMail]

In the OpenIDConnectService class, the IsLoggedIn property is implemented as:

public bool IsLoggedIn { get => !string.IsNullOrEmpty(AccessToken); }

However, this implementation is misleading:

1. The name and XML summary imply reliable login state detection, but the logic only checks whether the AccessToken is non-empty.
2. There is no validation of the token's validity, expiry, or whether it has been revoked.
3. This could lead to incorrect assumptions elsewhere in the application, where IsLoggedIn == true is interpreted as "user is currently authenticated".

Suggestion: Either rename the property to something more neutral (e.g. HasAccessToken) or implement a token validation there.