Add family join confirmation type

[ezhevita]

Checklist

• I read and understood the Contributing Guidelines.
• This is not a duplicate of an existing merge request.
• I believe this falls into the scope of the project and should be part of the built-in functionality.
• My code follows the code style of this project.
• I have added tests to cover my changes, wherever they are necessary.
• All new and existing tests pass.

Changes

New functionality

Add support for family join confirmation type, also log text type when encountering a confirmation with the unknown type.

Changed functionality

None

Removed functionality

None

Additional info

Logging text type is future-proofing so the log message itself would be enough to add a new type.

[ezhevita]

full confirmation json body (numbers are partially redacted):

{
    "type": 11,
    "type_name": "Join Steam family",
    "id": "15123456789",
    "creator_id": "9021234567890123456",
    "nonce": "14071234567890123456",
    "creation_time": 1710890000,
    "cancel": "Ignore",
    "accept": "Join",
    "icon": null,
    "multi": false,
    "headline": "Join this Steam family.",
    "summary": [
        ""
    ],
    "warn": null
}

[JustArchi]

Thanks! 🏆