[BUG] aggregate put_all not working with nested keys

[Psych0meter]

Describe the bug
It seems that the put_all aggregate function only works with "root" keys, and do not add new nested keys.

For example, I have these 2 postfix events that I need to aggregate, based on /host/id and /email/local_id :

{
  "@timestamp": "2024-01-19T13:25:35.503436Z",
  "postfix": {
    "nrcpt": "1",
    "size": "17603"
  },
  "application": "postfix",
  "host": {
    "id": "95e0888c1df24d79a4bc827f9636cca7"
  },
  "email": {
    "from": {
      "address": "EMAIL_FROM"
    },
    "local_id": "7A20930009B"
  },
  "message": "queue active"
}

{
  "@timestamp": "2024-01-19T13:25:35.527242Z",
  "postfix": {
    "relay": "localhost[::1]:24",
    "delays": "0/0/0/0.02",
    "dsn": "2.1.5",
    "delay": "0.03",
    "status": "sent"
  },
  "application": "postfix",
  "host": {
    "id": "95e0888c1df24d79a4bc827f9636cca7"
  },
  "email": {
    "local_id": "7A20930009B",
    "to": {
      "address": "EMAIL_TO"
    }
  },
  "test": "OK"
}

The put_all function only add keys that are at the '/' level of the JSON, and drop the other keys :

{
  "@timestamp": "2024-01-19T13:25:35.503436Z",
  "postfix": {
    "nrcpt": "1",
    "size": "17603"
  },
  "application": "postfix",
  "host": {
    "id": "95e0888c1df24d79a4bc827f9636cca7"
  },
  "email": {
    "from": {
      "address": "EMAIL_FROM"
    },
    "local_id": "7A20930009B"
  },
  "message": "queue active",
  "test": "ok"
}

To Reproduce
Steps to reproduce the behavior:

pipeline:
    processor:
    - aggregate:
        identification_keys:
          - "/host/id"
          - "/email/local_id"
        action:
          put_all:
        group_duration: "10s"
        aggregate_when: '/email/local_id != null'

Expected behavior
It needs to create the missing entries in the nested keys :

{
  "@timestamp": "2024-01-19T13:25:35.503436Z",
  "postfix": {
    "nrcpt": "1",
    "size": "17603",
    "relay": "localhost[::1]:24",
    "delays": "0/0/0/0.02",
    "dsn": "2.1.5",
    "delay": "0.03",
    "status": "sent"
  },
  "application": "postfix",
  "host": {
    "id": "95e0888c1df24d79a4bc827f9636cca7"
  },
  "email": {
    "from": {
      "address": "EMAIL_FROM"
    },
    "to": {
      "address": "EMAIL_TO"
    }
    "local_id": "7A20930009B"
  },
  "message": "queue active",
  "test": "ok"
}

Environment (please complete the following information):

• latest dataprepper docker image (2.6.1)