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.

model/config.go

@@ -1144,6 +1144,7 @@ type LdapSettings struct {
 	NicknameAttribute  *string
 	IdAttribute        *string
 	PositionAttribute  *string
+	LoginIdAttribute   *string
 
 	// Synchronization
 	SyncIntervalMinutes *int
@@ -1227,6 +1228,12 @@ func (s *LdapSettings) SetDefaults() {
 		s.PositionAttribute = NewString(LDAP_SETTINGS_DEFAULT_POSITION_ATTRIBUTE)
 	}
 
+	// For those upgrading to the version when LoginIdAttribute was added
+	// they need IdAttribute == LoginIdAttribute not to break
+	if s.LoginIdAttribute == nil {
+		s.LoginIdAttribute = s.IdAttribute
+	}
+
 	if s.SyncIntervalMinutes == nil {
 		s.SyncIntervalMinutes = NewInt(60)
 	}
@@ -2074,6 +2081,10 @@ func (ls *LdapSettings) isValid() *AppError {
 		if *ls.IdAttribute == "" {
 			return NewAppError("Config.IsValid", "model.config.is_valid.ldap_id", nil, "", http.StatusBadRequest)
 		}
+
+		if *ls.LoginIdAttribute == "" {
+			return NewAppError("Config.IsValid", "model.config.is_valid.ldap_login_id", nil, "", http.StatusBadRequest)
+		}
 	}
 
 	return nil

model/switch_request.go

@@ -15,7 +15,7 @@ type SwitchRequest struct {
 	Password       string `json:"password"`
 	NewPassword    string `json:"new_password"`
 	MfaCode        string `json:"mfa_code"`
-	LdapId         string `json:"ldap_id"`
+	LdapLoginId    string `json:"ldap_id"`
 }
 
 func (o *SwitchRequest) ToJson() string {