Unsupported Devices Should not be referenced in groups

As discussed in Discord, the official Hue App gets very confused if a group in state.yaml mentions a child that has no other references.

Snippet from convo:

```
2025-01-30T19:27:42.802Z INFO bifrost::z2m > [server1] Adding light IeeeAddress(0017880108e24db8): [Back Deck Bulb] (LTA003)
2025-01-30T19:27:42.802Z DEBUG bifrost::z2m > [server1] Ignoring unsupported device Back Deck String
2025-01-30T19:27:42.805Z DEBUG bifrost::z2m > [server1] room/f4a64f2a-70e8-56d0-bbcc-ed8c8db2e9a2 (Back Deck) is new, adding..
```

Here's the entry for the group from state.yaml:

```yaml
f4a64f2a-70e8-56d0-bbcc-ed8c8db2e9a2:
type: room
children:
- rid: e0004380-6f53-5b38-8ef8-5a65931317bf
rtype: device
- rid: '1c792ce2-727c-565c-b0ff-411412108797'
rtype: device
metadata:
name: Back Deck
archetype: home
services:
- rid: '62400369-a1de-58f1-aed3-06c75b599617'
rtype: grouped_light
```

The string "e0004380-6f53-5b38-8ef8-5a65931317bf" occurs 5 times in state.yaml (and indeed seems to be Back Deck Bulb) but "1c792ce2-727c-565c-b0ff-411412108797" only occurs this once during the group entry, and I suspect it's the "ignored" device.