MM-4998 Adding LoginIdAttribute to allow LDAP users to change their login ID without losing their account (#8756)

* Adding LoginIdAttribute

* Modifying LDAP to use loginIDAttribute.

* Adding IDAttribute migration and AD objectGUID support.

* Removing unused idea.

* Fix typo.

app/ldap.go

@@ -40,7 +40,7 @@ func (a *App) TestLdap() *model.AppError {
 	return nil
 }
 
-func (a *App) SwitchEmailToLdap(email, password, code, ldapId, ldapPassword string) (string, *model.AppError) {
+func (a *App) SwitchEmailToLdap(email, password, code, ldapLoginId, ldapPassword string) (string, *model.AppError) {
 	if a.License() != nil && !*a.Config().ServiceSettings.ExperimentalEnableAuthenticationTransfer {
 		return "", model.NewAppError("emailToLdap", "api.user.email_to_ldap.not_available.app_error", nil, "", http.StatusForbidden)
 	}
@@ -63,7 +63,7 @@ func (a *App) SwitchEmailToLdap(email, password, code, ldapId, ldapPassword stri
 		return "", model.NewAppError("SwitchEmailToLdap", "api.user.email_to_ldap.not_available.app_error", nil, "", http.StatusNotImplemented)
 	}
 
-	if err := ldapInterface.SwitchToLdap(user.Id, ldapId, ldapPassword); err != nil {
+	if err := ldapInterface.SwitchToLdap(user.Id, ldapLoginId, ldapPassword); err != nil {
 		return "", err
 	}
 
@@ -95,7 +95,7 @@ func (a *App) SwitchLdapToEmail(ldapPassword, code, email, newPassword string) (
 		return "", model.NewAppError("SwitchLdapToEmail", "api.user.ldap_to_email.not_available.app_error", nil, "", http.StatusNotImplemented)
 	}
 
-	if err := ldapInterface.CheckPassword(*user.AuthData, ldapPassword); err != nil {
+	if err := ldapInterface.CheckPasswordAuthData(*user.AuthData, ldapPassword); err != nil {
 		return "", err
 	}