Merge pull request #654 in ZP/z-push from feature/ZP-1357-private-items-when-impersonating to develop

* commit '5220fd16':
  ZP-1357 Simplify check if the user is impersonated for folder origin.
  ZP-1357 Remove unnecessary log output.
  ZP-1357 Fixed GetMainUser() return type.
  ZP-1357 Get authenticated and impersonated user from the backend instead of from the request.
  ZP-1357 Remove unnecessary log output.
  ZP-1357 Prevent editing private items in impersonated folder. Added impersonated folder origin.