- make `UserActivity.InGame` and derive that to `InSoloGame` and `InMultiplayerGame`
- rename `SoloGame` to `InSoloGame`
- rename `MultiplayerGame` to `InMultiplayerGame`
There are 3 modes: enabled, limited, and disabled.
The limited mode hides identifiable information such as username, rank, and
(if participating in one) multiplayer lobby name.