Allow customization of LDAP login fields (#2692)

config/config.json

@@ -145,7 +145,9 @@
         "UsernameAttribute": "",
         "IdAttribute": "",
         "SkipCertificateVerification": false,
-        "QueryTimeout": 60
+        "QueryTimeout": 60,
+        "LoginFieldName": "",
+        "PasswordFieldName": ""
     },
     "ComplianceSettings": {
         "Enable": false,