Add peer interface annotation for physical interfaces

[felix-kaestner]

This patch introduces the PhysicalInterfaceNeighborLabel label which
references the peer Interface resource on the other end of a physical
link. The label can be used by users to declare expected cabling, or
by controllers to reflect actual cabling discovered via neighbor
discovery protocols (e.g., LLDP).

The label value must be the name of another Interface resource in the
same namespace. It is only valid for interfaces of type Physical.

Additionally, a PhysicalInterfaceNeighborRawAnnotation annotation is
introduced for interfaces connected to unmanaged devices (devices
without an Interface resource). The annotation value format is
"chassisID::portID" where chassisID is the LLDP chassis identifier
and portID is the LLDP port identifier.

Both the label and annotation are mutually exclusive - an interface
cannot have both set at the same time.

[SchwarzM]

do we want to use an annotation in this case ? this makes it harder for cli tools to display / filter for it correctly I think

[felix-kaestner]

do we want to use an annotation in this case ? this makes it harder for cli tools to display / filter for it correctly I think

@SchwarzM Changed to a label with a same-namespace constraint - the value is now just the interface name (no namespace prefix). This enables filtering while keeping the value label-compatible.

[nikatza]

Nice, thanks for the update!

[github-actions]

Merging this branch will increase overall coverage

Impacted Packages	Coverage Δ	🤖
github.com/ironcore-dev/network-operator/api/core/v1alpha1	0.00% (ø)
github.com/ironcore-dev/network-operator/internal/webhook/core/v1alpha1	90.48% (+1.71%)	👍

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Coverage by file

Changed files (no unit tests)

Changed File	Coverage Δ	Total	Covered	Missed	🤖
github.com/ironcore-dev/network-operator/api/core/v1alpha1/groupversion_info.go	0.00% (ø)	0	0	0
github.com/ironcore-dev/network-operator/internal/webhook/core/v1alpha1/interface_webhook.go	93.62% (+10.28%)	47 (+23)	44 (+24)	3 (-1)	🎉

Please note that the "Total", "Covered", and "Missed" counts above refer to code statements instead of lines of code. The value in brackets refers to the test coverage of that file in the old version of the code.

Changed unit test files

• github.com/ironcore-dev/network-operator/internal/webhook/core/v1alpha1/interface_webhook_test.go