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.

config/default.json

@@ -263,6 +263,7 @@
         "NicknameAttribute": "",
         "IdAttribute": "",
         "PositionAttribute": "",
+        "LoginIdAttribute": "",
         "SyncIntervalMinutes": 60,
         "SkipCertificateVerification": false,
         "QueryTimeout": 60,