[V4] Launches endpoint doesn't retrieve launchpad details when populated
Populating the field `launchpad` inside the Launches endpoint doesnt' retrieve the 'details' field.

Options:
```
{
    "options": {
        "populate": [
            {
                "path": "launchpad"
            }
        ]
    }
}
```

Output:
```
            "launchpad": {
                "name": "Kwajalein Atoll",
                "full_name": "Kwajalein Atoll Omelek Island",
                "locality": "Omelek Island",
                "region": "Marshall Islands",
                "timezone": "Pacific/Kwajalein",
                "latitude": 9.0477206,
                "longitude": 167.7431292,
                "launch_attempts": 5,
                "launch_successes": 2,
                "rockets": [
                    "5e9d0d95eda69955f709d1eb"
                ],
                "launches": [
                    "5eb87cd9ffd86e000604b32a",
                    "5eb87cdaffd86e000604b32b",
                    "5eb87cdbffd86e000604b32c",
                    "5eb87cdbffd86e000604b32d",
                    "5eb87cdcffd86e000604b32e"
                ],
                "status": "retired",
                "id": "5e9e4502f5090995de566f86"
            },
```