Subject search for blog not working on dev

[edwoodward]

Description

The data structure of the json stored for subjects on dev is different than it was during local development. The original structure was [{'type': 'subject', 'value': [{'subject': 4}], 'id': '98a80440-8b7c-4857-89ee-7bebbc87b904'}]

The structure on dev is [{'type': 'subject', 'value': [{'type': 'item', 'value': {'subject': 1, 'featured': False}, 'id': '78e7e9c1-487f-42bb-b960-4a2901aa3150'}]

The code needs to work with the structure on dev. Blog Collections and content types have the same issue.

Acceptance Test

• subject search for blog posts works - https://dev.openstax.org/apps/cms/api/search/?subjects=Math