DD-527 Restructure license and custom terms in dataset JSON

[mderuijter]

Create dataset with custom and standard license and use following curl command:

curl -s -H X-Dataverse-key:{apiToken} 'http://localhost:8080/api/datasets/:persistentId/versions/{:draft OR 1.0}?persistentId={doi:10.5072/DAR/BXBIEB}' | jq

Should result in:

{
  "status": "OK",
  "data": {
    "id": 2,
    "datasetId": 3,
    "datasetPersistentId": "doi:10.5072/DAR/BXBIEB",
    "storageIdentifier": "s3://10.5072/DAR/BXBIEB",
    "versionState": "DRAFT",
    "lastUpdateTime": "2021-07-07T09:53:30Z",
    "createTime": "2021-07-07T09:37:17Z",
    "license": {
      "label": "CUSTOM",
      "uri": "https://dar.dans.knaw.nl/api/datasets/:persistentId/versions/:draft/customlicense?persistentId=doi:10.5072/DAR/BXBIEB"
    }, 
    ....
} 

[janvanmansum]

@mderuijter : Oops, merged the wrong PR. I'll test this and then see if it needs to be reverted.