MM-16860 Support Guest Authentication via SAML (#12622)

* add GuestAttribute setting

* Add Constant

* add isdefault_guest_attribute to diagnostics.go

* revert changes to go.mod

* revert changes to LdapInterface.go

* revert changes to LdapInterface.go

* revert changes to LdapInterface.go

app/diagnostics.go

@@ -509,6 +509,7 @@ func (a *App) trackConfig() {
 		"isdefault_scoping_idp_provider_id":   isDefault(*cfg.SamlSettings.ScopingIDPProviderId, ""),
 		"isdefault_scoping_idp_name":          isDefault(*cfg.SamlSettings.ScopingIDPName, ""),
 		"isdefault_id_attribute":              isDefault(*cfg.SamlSettings.IdAttribute, model.SAML_SETTINGS_DEFAULT_ID_ATTRIBUTE),
+		"isdefault_guest_attribute":           isDefault(*cfg.SamlSettings.GuestAttribute, model.SAML_SETTINGS_DEFAULT_GUEST_ATTRIBUTE),
 		"isdefault_first_name_attribute":      isDefault(*cfg.SamlSettings.FirstNameAttribute, model.SAML_SETTINGS_DEFAULT_FIRST_NAME_ATTRIBUTE),
 		"isdefault_last_name_attribute":       isDefault(*cfg.SamlSettings.LastNameAttribute, model.SAML_SETTINGS_DEFAULT_LAST_NAME_ATTRIBUTE),
 		"isdefault_email_attribute":           isDefault(*cfg.SamlSettings.EmailAttribute, model.SAML_SETTINGS_DEFAULT_EMAIL_ATTRIBUTE),