[detectors/azure] Add AKS detector — port from resourcedetectionprocessor azure/aks

[paulojmdias]

Problem Statement

collector-contrib/processor/resourcedetectionprocessor/internal/azure/aks implements an AKS resource detector that detects when the process is running on Azure Kubernetes Service. There is currently no equivalent in go-contrib/detectors/azure/, which means AKS detection is only available to collector-contrib pipelines and not to any Go SDK user.

Proposed Solution

Add a new detectors/azure/aks (or extend detectors/azure/) package implementing the AKS detector as a resource.Detector, ported from the collector-contrib implementation, so that collector-contrib/processor/resourcedetectionprocessor can delegate to it and any other Go SDK user can adopt it.

Prior Art

• Collector-contrib implementation to port from: processor/resourcedetectionprocessor/internal/azure/aks
• Existing go-contrib azure detectors: detectors/azure/
• Tracking issue: [processor/resourcedetection] Align detectors with opentelemetry-go SDK detectors opentelemetry-collector-contrib#48159

Additional Context

What the collector-contrib detector does:

• Checks for the KUBERNETES_SERVICE_HOST environment variable to confirm it is running on Kubernetes.
• Calls the Azure Instance Metadata Service to confirm it is running in Azure.
• Parses the resource group name to extract the AKS cluster name.
• Emits: cloud.provider (azure), cloud.platform (azure_aks), k8s.cluster.name.