Auth: Introduce authn.SSOClientConfig to get client config from SSOSettings service (#94618)
* wip
* possible solution
* Separate interface for SSO settings clients
* Rename interface
* Fix tests
* Rename
* Change GetClientConfig to comma ok idiom
(cherry picked from commit 50a635bc7e)
errAPIKeyOrgMismatch=errutil.Unauthorized("api-key.organization-mismatch",errutil.WithPublicMessage("API key does not belong to the requested organization"))