Proposal: support forwarding UDP ports

> [!NOTE]
> I understand this feature may not be as simple as it sounds. It will likely mean changing the editors to support forwarding udp ports as the current implementations likely do not leverage docker for it.
>
> Anyway, I'm opening this issue to start the discussion because I haven't found one elsewhere.

It would be great if the following were possible:

```json
{
"forwardPorts": ["5683/udp"]
}
```

Or maybe:

```json
{
"forwardPorts": [5683],
"portsAttributes": {
"5683": {
"label": "CoAP",
"onAutoForward": "silent",
"protocol": "udp"
}
}
}
```

---

A workaround is to use the older `appPort`:

```json
{
"appPort": ["5683/udp"]
}
```

But `appPort` has limitations that `forwardPorts` don't have. For example, `appPort` ports cannot be labeled through `portAttributes`.

Beginne mit der Prüfung der Definitionen von forwardPorts, portsAttributes und appPort in der Spezifikation und untersuche anschließend die im Issue referenzierten Editor-Implementierungen. Vergleiche den bestehenden UDP-Workaround für appPort mit dem angeforderten Verhalten von forwardPorts und definiere vor der Implementierung das unterstützte Schema, die Kennzeichnung, die Protokollbehandlung und die Kompatibilitätserwartungen.

Vom Indexierungsmodell aus dem Issue-Text verfasst.