Fix missing annotations in json download

[Era-Dorta]

This PR adds the annotation data to the json that is downloaded when you click on the "Download results (JSON)" in the admin panel.

The json is formatted like so:

{
    "hit_id": "35c236724410e66e214c786aad51d9d813bdef9e7203d123ed9ebeddf512e4c1",
    "nodes": {
        "1": {
            "responses": [
                {
                    "created": "2024-05-02 13:07:24.066921",
                    "submitted": "False",
                    "state": {
                        "selectedAnnotationIndex": 0,
                        "mediaPaused": null
                    },
                    "annotations": [],
                    "prolific_id": [
                        "annotator3"
                    ]
                }
            ]
        },
        "2": {
            "responses": [
                {
                    "created": "2024-05-02 13:07:24.066926",
                    "submitted": "False",
                    "state": {
                        "selectedAnnotationIndex": 0,
                        "mediaPaused": null
                    },
                    "annotations": [
                        [0, 0, 0, 0, 0, ........ THIS IS ACTUALLY QUITE LONG, 7200 LINES BUT WITHOUT LINE BREAKS ........., 0, 1, 1]
                   ],
                    "prolific_id": [
                        "annotator1"
                    ]
                }
            ]
        }
    },
    "journeys": [
        {
            "nodes": [
                1
            ]
        },
        {
            "nodes": [
                2
            ]
        },
    ]
}