Update PluginFetchResourceListFromDrupal to work with JSON:API 8.x-2.x

[seth-shaw-unlv]

The JSON:API module shifted from using simple strings for links (8.x-1.x) to link objects (8.x-2.x). E.g. What once looked like:

"links": {
  "next": "http://localhost:8000/jsonapi/node/islandora_object?page[limit]=50&page[offset]=50&sort=-changed"
}

now looks like:

"links": {
  "next": {
    "href": "http://localhost:8000/jsonapi/node/islandora_object?page[limit]=50&page[offset]=50&sort=-changed"
  }
}

As 8.x-2.x is the recommended branch and it will be incorporated into Drupal 8.7 Core we should update PluginFetchResourceListFromDrupal to conform to the new structure.

[mjordan]

Closed with 85bd81d2b0b16b818fda2521975261f42d756ba5.