Support for multiple logout urls

The Gainsight community platform supports several external SSO providers like OpenID, SAML etc., but logout is being handled insufficiently. Standard end_session / logout urls are missing from these integrations. One can configure a logout url for their community with the help of support, but the platform only supports one logout url.

In the future we want to have two SSOs in use in our community: one for end users and one for staff members. We have ran into a challenge while configuring this as the Gainsight community portal only supports one logout url.

With separate logout urls we'll make sure the sessions are ended upon logout. Without separate logout urls the sessions are not ended correctly. This creates a risk for example for users using shared computers.