Issue 50390 - Add Managed Entries Plug-in Config Entry schema
Description: Add AttributeTypes and an ObjectClass to Managed Entries
Plug-in Configuration entry schema.
Fix MEPConfigs(DSLdapObjects) accordingly.
https://pagure.io/389-ds-base/issue/50390
Reviewed by: mreynolds (Thanks!)
(cherry picked from commit 31c89d3bbd0bcfea71b4e6be912ad4bb9f43e171)