AuthN: move oauth token hook into session client (#76688)

* Move rotate logic into its own function

* Move oauth token sync to session client

* Add user to the local cache if refresh tokens are not enabled for the provider so we can skip the check in other
requests

pkg/services/authn/authnimpl/sync/user_sync.go

@@ -394,4 +394,5 @@ func syncSignedInUserToIdentity(usr *user.SignedInUser, identity *authn.Identity
 	identity.LastSeenAt = usr.LastSeenAt
 	identity.IsDisabled = usr.IsDisabled
 	identity.IsGrafanaAdmin = &usr.IsGrafanaAdmin
+	identity.AuthenticatedBy = usr.AuthenticatedBy
 }