Get creatives

Allows a buyer from an external DSP to get the creatives that were sent for approval.
In Hivestack, creative approval is done at the creative file level. The approval status
can be retrieved in the approval_state of the returned media files. Only the approved media files
will be selected to play.

The approval_state allows 3 different integer values. They are:

  1. Pending
  2. Approved
  3. Rejected