greenhouse: activity_feed should be flattened

[mdibaiee]

I think the issue is very similar to what we have seen before: an array API response which should actually be flattened, but is just emitted as-is (previously we have seen this with amazon ads). The only solution is to patch the connector to emit individual objects from the response arrays instead of just emitting the whole document

The API endpoint is: https://developers.greenhouse.io/harvest.html#the-activity-feed-object

Output example:

  "notes": [
    {
      "id": 123456,
      "created_at": "2014-03-26T20:11:40Z",
      "body": "Very mysterious.",
      "user": {
        "id": 512,
        "first_name": "Sayid",
        "last_name": "Jarrah",
        "name": "Sayid Jarrah",
        "employee_id": "12345"
      },
      "private": false,
      "visiblity": "public",
      "visibility": "public"
    }
  ],
  "emails": [
    {
      "id": 234675,
      "created_at": "2014-04-01T15:55:06Z",
      "subject": "Regarding your application",
      "body": "Hey John,  just wanted to touch base!",
      "to": "john.locke@example.com",
      "from": "boone.carlyle@example.com",
      "cc": "sam.smith@example.com",
      "user": {
        "id": 214,
        "first_name": "Boone",
        "last_name": "Carlyle",
        "name": "Boone Carlyle",
        "employee_id": "67890"
      }
    }
  ],
  "activities": [
    {
      "id": 6756789,
      "created_at": "2014-04-01T15:55:29Z",
      "subject": "Candidate Rejected",
      "body": "Reason: Lacking hustle\n\nThis candidate turned out to be problematic for us...",
      "user": {
        "id": 214,
        "first_name": "Boone",
        "last_name": "Carlyle",
        "name": "Boone Carlyle",
        "employee_id": "67890"
      }
    },
    {
      "id": 6757869,
      "created_at": "2014-03-26T20:26:38Z",
      "subject": "Candidate Stage Change",
      "body": "John Locke was moved into Recruiter Phone Screen for Accounting Manager on 03/27/2014 by Boone Carlyle",
      "user": {
        "id": 214,
        "first_name": "Boone",
        "last_name": "Carlyle",
        "name": "Boone Carlyle",
        "employee_id": "67890"
      }
    }
  ]
}

This connector has a single stream called activity_feed which just outputs this, but instead I think we need to have three different streams: activity_feed_notes, activity_feed_emails and activity_feed_activities