CDB3-4659 Add systemDateModifiedField to each object

Problem: system migrations does not update dateModied field because of it's business purpose

Proposal: add meta systemDateModified field which would be updated in case if we manually update object or make object migrations

add _meta field:

{
   "_id": <Object-id>,
   "dateModified": <datetime>,
   ....

  "_meta": {
      "systemDateModified": <datetime>
  }

}