Add logout functionality to OIDC feature

[lgadban]

Is your feature request related to a problem? Please describe.
Currently there is no mechanism by which you can "log out" of an existing "session" that was established via the OIDC feature.

Describe the solution you'd like
An option to logout/destroy the session established via OIDC

Describe alternatives you've considered
If the IdP supports logout functionality, that can be used, but it still will not logout of the Gloo session

Additional context
OIDC spec should be used, e.g. https://openid.net/specs/openid-connect-session-1_0.html#RPLogout

[kevinnesta]

Hi @lgadban ,
I'm really interested in that enhancement! 👍