Fix user role not updated by gatekeeper

[filippomc]

If a user role is updated on keycloak, the gatekeeper does not see the change.
Let's say that a user tries to access an application A which is not allowed -> 403 page.
If the admin gives the role that authorizes the user to enter the application and the user refreshes the page, still the user is not authorized.

So the gatekeeper uses old information (probably cached) about the user to check the access.

Possible solutions:

• Reduce the time the gatekeeper refreshes the user information from keycloak
• Improve the 403 page by giving a logout link so that the user can retry.

[filippomc]

The keycloak parameter "access token lifespan" defines the expiration time for the token used by the gatekeeper