Support for configuring external token exchange

[Xymanek]

Ref: https://www.keycloak.org/docs/25.0.1/securing_apps/#_grant_permission_external_exchange (permissions are same for internal-to-external and external-to-internal exchange).

Currently there is no support for configuring external IdP permissions, only keycloak_group_permissions, keycloak_openid_client_permissions and keycloak_users_permissions (none of which can be coerced into working with IdP due to IdPs having different scope setup). I was able to workaround using restapi, but it would definitely be far more convenient to have proper support from this provider (which is great for everything else!).

Are contributions accepted?

[stale-vegait]

What about this one keycloak_identity_provider_token_exchange_scope_permission? We use this one with client policy to configure internal->external token exchange.