Remove feds first from APBs before removing the feds

[yoctozepto]

At the moment, removing federations does not consider Attestation Policy Bindings (APBs). It rather should as it leaves a broken config.

There are two ways to go:

1. remove APBs with the removed federation (simpler)
2. block federation removal if APBs still reference it (safer, analogous to removing APs being blocked by existing APBs)

[markgoddard]

Option 3: remove the APFederation entry related to the deleted federation, but leave the binding intact.

[yoctozepto]

Option 3: remove the APFederation entry related to the deleted federation, but leave the binding intact.

Doing that automatically might be tricky as there could be overlaps with non-federated bindings.

[yoctozepto]

Idea: verify with Connect.