Narrow down switch API.

[Gerrit91]

Description

To me it feels like the switch API is a bit too broad and there are no descriptions anywhere what fields are used in which circumstances, potentially even leading to possibilities to misuse the API.

Here is an idea to narrow down the API slightly:

1. Disallow admins to send nics and os, these come from register (also remove duplicate updated_at timestamp?)
2. Create a register request that really only contains the fields that the metal-core is expected to set

Used AI-Tools ✨

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[Gerrit91]

This results in quite huge server changes (I tried already), so I am unsure if we really want this. But somehow I am not 100% convinced by how the API was defined either. :s